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IBM Multiprise 3000 Reference Manual

Enterprise server internal disk subsystem
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IBM
S/390
Internal Disk Subsystem:

Reference Guide

Multiprise 3000 Enterprise Server
R
SA22-1025-00

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Summary of Contents for IBM Multiprise 3000

  • Page 1: Reference Guide

    S/390 Internal Disk Subsystem: Reference Guide Multiprise 3000 Enterprise Server SA22-1025-00...
  • Page 3 S/390 Internal Disk Subsystem: Reference Guide SA22-1025-00...
  • Page 4  Copyright International Business Machines Corporation 1999. All rights reserved. Note to U.S. Government Users — Documentation related to restricted rights — Use, duplication or disclosure is subject to restrictions set forth in GSA ADP Schedule Contract with IBM Corp.

  • Page 5: Table Of Contents

    ........ Copyright IBM Corp. 1999...
  • Page 6 End-of-File ........Chapter 4. Command Descriptions .
  • Page 7 Write Track Data 4-102 ........Sense Commands 4-104 .
  • Page 8 ......IBM Agreement for Licensed Internal Code .....

  • Page 9: Chapter 1. Overview Of The S/390 Internal Disk Subsystem

    The maximum configuration has one CPC frame and two expansion frames. The Multiprise 3000 has a minimum Internal Disk capacity of 72GBs and a maximum capacity (inclusive of two expansion frames) of 792GBs. The Internal Disk Subsystem offers the following advantages:...

  • Page 10: Host Processor

    Internal Disk RAID Fast Write (IDRFW) provides a fast write capability through the SSA adapter card. Host Processor Internal Disk is packaged with the Multiprise 3000 which is a unique card on board package that takes advantage of: Integrated RAID Storage...

  • Page 11: Raid Disk Arrays

    The high performance 18GB UltraStar 18ZX which has a rotational speed of 10,020 rpm is the HDD used on Internal Disk for the Multiprise 3000. Along with its high rpm and lower latency, the 18GB UltraStar 18ZX has state of the art data rate and seek times.

  • Page 12: Internal Disk Raid Fast Write

    HDD Buffer Capacity 4 MBytes Internal Disk RAID Fast Write To improve write performance, Internal Disk for Multiprise 3000 includes a 32MB Non-Volatile RAM (NVRAM) memory. The NVRAM is incorporated on the SSA adapter card. Some advantages of the NVRAM addition are: The NVRAM is a centralized storage that dynamically services the most active HDDs on the SSA adapter card.

  • Page 13: Ckd Emulation

    CKD Emulation The Internal Disk Subsystem processes ECKD/CKD channel programs which presuppose variable length Count, Key, and Data fields like those of a 3990 subsystem. Internal Disk constructs CKD track images in memory and executes the ECKD and CKD channel programs, which operate on byte boundaries, against the images.
  • Page 14 Background Scrubbing Background scrubbing is provided by Internal Disk to further reduce the probability of customer loss of data. There is a small possibility that after a data failure occurs, the redundancy data is also found to be unreadable, resulting in loss of data to the customer. Data scrubbing is provided to help ensure that all the data in the disk subsystem is periodically proven readable so that if a failure occurs, the redundancy exists to fully restore the original data.

  • Page 15: Long Busy

    CPC memory as a subsystem read cache across all Internal Disk Subsystem devices. The read cache capacity can range from 32MB to 2GB. The 2GB cache can only be selected on a Multiprise 3000 which has 4GB Chapter 1. Overview of the S/390 Internal Disk Subsystem...

  • Page 16: Ssa Adapter Card

    The SSA adapter card supplies an SSA interface that operates at up to 40MB/sec for connection of the HDDs. Two levels of physical interface conversion occur between the Multiprise 3000 main memory and the SSA HDDs. The host Multiprise 3000 provides a Self Timed Interface (STI). A special purpose electronics bridge called the STI-PCI bridge converts the STI to the upper interface of the SSA adapter card.

  • Page 17: Logical Volume Address Resolution

    A particular logical volume is reached via an addressing hierarchy: CHPID Address Only one CHPID address is used for all of the logical volumes on a Multiprise 3000. The address is assigned as x'FD'. Chapter 1. Overview of the S/390 Internal Disk Subsystem...

  • Page 18: Internal Disk Configuration Granularity

    Control Unit Logical Address Each of the three enclosures of a fully populated Multiprise 3000 contains a disk subsystem with a logical 3990 mod 2 control unit. The logical control unit that controls the HDD enclosure in the CPC frame is assigned control unit logical address x'0'.

  • Page 19: Commands And Facilities Not Supported

    The DSD CHPID can be dedicated or shared, or reconfigurable (REC). There is only one valid DSD path on the Multiprise 3000. It is x'FD'. IOCP requires that the control unit type defined on a DSD CHPID begin with "3990".

  • Page 20: Ras Characteristics

    defined for each RAID-5 array. Each logical volume may only be defined to one control unit. The Self Timed Interface (STI) connection between the processor and the SSA adapter is specified as the single DSD CHPID. Control unit (CNTLUNIT) statements are defined for each SSA loop in the storage facility.

  • Page 21: Chapter 2. Processing Commands And Presenting Status

    Test Subchannel Reset Channel path Channel Subsystem Call - Reset Control Unit. The Manual IBM Enterprise Systems Architecture/390 Principles of Operation describes the above instructions. Internal Disk Subsystem supports all count-key-data (CKD) and extended count-key-data (ECKD) channel commands defined in this manual.
  • Page 22 Table 2-1. Status Byte Name Attention Status Modifier Control-Unit End Busy Channel End Device End Unit Check Unit Exception Attention (Bit 0) Bit 0 is set to a ‘1’: With device end and unit exception to show a state transition. (See “State-Change Interruption”...
  • Page 23 Channel End (Bit 4) Bit 4 is set to a ‘1’: At the end of parameter transfer or data transfer of each command. At the end of command execution for commands that have no parameter or data transfer. Device End (Bit 5) Bit 5 is set to a ‘1’: When alone or with channel end to show that a logical volume is available for use.

  • Page 24: Initial Status Byte

    Initial Status Byte The initial status byte is zero for all valid non-immediate commands with the following exceptions: Logical volume is busy – Busy Bit alone is returned. Status condition is pending – The pending status combination plus Busy Bit is returned.

  • Page 25: State-Change Status

    Channel end has been previously accepted and the operation is now complete, but device end has not been presented to the channel. Busy status has previously been sent and the logical volume is now not busy. The resulting device end has not been presented to the channel. The logical volume changed states, and that status has not been presented to the channel.
  • Page 26 chain. These command chains may compete for data within a single logical volume. Only one data transfer chain is active on a logical volume at a time. I/O Queuing Multiple LPARs may issue CCW chains that require the same logical volume. Internal Disk provides for queuing of command chains from the various LPARs and provides for orderly execution of the chains.
  • Page 27 Table Column Definitions The table that follows is intended to show the actions taken for the bypass commands particularly. Table 2-2 on page 2-8 summarizes the status presented to commands when the subsystem or device is in one of the states described in the following text.
  • Page 28 Internal Disk Subsystem Reference Guide...

  • Page 29: Listing Of Commands Appearing In Table

    Listing of Commands Appearing in Table 3 A full listing of all of the command names and mnemonics that are executed by Internal Disk appears in Table 7 on page 4-3. For convenience in referring to the preceding table a list of only the commands that appear in the table is shown below.

  • Page 30: Channel Command Retry–Control Unit Initiated

    uses channel command retry to disconnect from the channel and recover from the error or wait for the required resource. Channel Command Retry–Control Unit Initiated The control unit initiates retries for delayed selection and device orientation. Delayed Selection and Device Orientation Internal Disk accepts initial selection without selecting the physical device.
  • Page 31 alone subsystem that has external interfaces and interface switches in its attachment topology. The first selection of all other logical volumes on the reset interface will be unit checked with sense data that includes equipment check. The Internal Disk Subsystem procedure is that the first selection of all logical volumes on the reset interface will receive unit check with sense data that includes equipment check.
  • Page 32 2-12 Internal Disk Subsystem Reference Guide...

  • Page 33: Chapter 3. Elements Of Data Access

    Data Access Access to data requires physically accessing the track (actually cache track image), finding a place on the track, and sometimes, searching for a specific record. The following text describes each of these operations.  Copyright IBM Corp. 1999...

  • Page 34: Track Accessing

    Track Accessing To access a specific track, the host program must first specify the desired cylinder and track. This positioning occurs without requiring the device to read any user data. When the track accessing operation completes, the track address (CCHH) is saved and maintained by the subsystem until changed by subsequent host commands.

  • Page 35: Record Accessing

    Record Accessing An associative addressing (search) operation can find a specific record, which causes the control unit to read some area from the device and compare (associate) it with a value from the channel. The Locate Record command or one of the search commands is used to do the search operation.

  • Page 36: File Protection

    See “Locate Record” on page 4-13 for a complete description. Note: Performance can be significantly affected by the way that Locate Record CCWs are used in the channel program. For example, two different channel programs can read two consecutive records on a track. One channel program has one Locate Record CCW followed by two read CCWs;...
  • Page 37 A-1. See also IBM 3380 Direct Access Storage Introduction and IBM 3390 Direct Access Storage Introduction. Chapter 3. Elements of Data Access...
  • Page 38 Internal Disk Subsystem Reference Guide...

  • Page 39: Chapter 4. Command Descriptions

    Program-Controlled Interruption (PCI): Bit 36 (format 0) or bit 12 (format 1), when ‘1’, causes the channel to generate an intermediate interruption condition by using the appropriate subchannel when the CCW takes control of the I/O operation.  Copyright IBM Corp. 1999...

  • Page 40: Exception Conditions

    Indirect Data Address (IDA): Bit 37 (format 0) or bit 13 (format 1), when ‘1’, specifies indirect data addressing. Suspend (S): Bit 38 (format 0) or bit 14 (format 1), when ‘1’, specifies suspension of channel-program processing. Note: Except for a Transfer in Channel (TIC) command, flag bit 39 (format 0) or bit 15 (format 1) must be zero.

  • Page 41: Defective/Alternate Track Operations

    If the next track is not in the defined extent, the operation ends with unit check status. The sense data includes File Protected. If the operation is a Locate Record Extended Operation code of Read Any or Write Any, the operation continues through index on the same track. Operations Outside the Domain of a Locate Record or Locate Record Extended Outside the domain of a Locate Record or Locate Record Extended, bit 0 of the...
  • Page 42 Table 4-3 (Page 2 of 3). List of Channel Commands Hex Code Command Name Mnemonic Page single-track Multitrack Mode Mode Read Commands Read Home Address 4-62 Read Record Zero 4-63 Read Count, Key, and Data RCKD 4-64 Read Key and Data 4-66 Read Data 4-68...
  • Page 43 Table 4-3 (Page 3 of 3). List of Channel Commands Hex Code Command Name Mnemonic Page single-track Multitrack Mode Mode Subsystem Commands Perform Subsystem Function – 4-130 Sense Subsystem Status SNSS – 4-136 Read Subsystem Data RSSD – 4-139 Note: (1) This command is valid on 3380 logical volumes, not on 3390 logical volumes. Chapter 4.

  • Page 44: List Of Channel Commands By Hex Code

    List of Channel Commands by Hex Code Following is a list of the same commands as in Table 4-3 on page 4-3. The commands are listed here in order by their hex codes, with the page location of the command descriptions. (MT) = Multitrack Mode. Hex Command Name Page Hex Command Name...

  • Page 45: Addressing And Control Commands

    Addressing and Control Commands None of the commands in this group transfer user data records between the Internal Disk and the host channel. However, most of the commands in this group require the host system to send control information, associated with the command, to the Internal Disk.

  • Page 46: Define Extent

    Define Extent Hex Code Data Address Count The main storage location of the first parameter byte. Description: The Define Extent command parameters define limits on operations that follow, provide a blocksize value, and specify cache controls for the channel program. This command resets orientation in the control unit. Chaining and Restrictions: Unit check status with the sense data containing command reject with format 0, message 2 occurs if: A Define Extent command is in the domain of a Locate Record or Locate...
  • Page 47 Table 4-5. Mask Byte Definition Byte 0 Bits Mask Byte Function Value 0–1 Write Control Permit all write operations except Write HA and Write R0 Inhibit all write operations Permit update write operations only Permit all write operations Reserved 3–4 Seek Control Permit all Seek commands Permit Seek Cylinder and Seek Head...
  • Page 48 Byte 0, Bits 3 and 4: Specify what seek commands and multitrack head switching operations to permit outside the domain of a Locate Record or Locate Record Extended. They have no effect on channel commands operating in the domain of a Locate Record or Locate Record Extended.
  • Page 49 Table 4-6 (Page 2 of 2). Global Attributes Byte Definition Byte 1 Bit Value Global Attributes Function Bits 3–5 Subsystem Operation Mode Normal cache replacement Bypass cache Inhibit cache loading Sequential access Sequential Prestage Record Access 110 – 111 Reserved. The Internal Disk Subsystem ignores these combinations and uses normal cache replacement.
  • Page 50 ‘100’ – Sequential Prestage: In the Internal Disk Subsystem, this setting is treated the same as Normal Cache Replacement. ‘101’ – Record Access: Indicates that there is little locality of reference of the data accessed by this channel program. Byte 1, Bit 6 – Reserved, must be zero: If this bit is set to ‘1’, the command is terminated with unit check status.

  • Page 51: Locate Record

    The data field bytes are all equal to zero. If Bit 5 is set to zero, the Record Zero differs from the above only in the data field content. The data field bytes are those that are provided in the parameters of the Write Record Zero command.
  • Page 52 The control unit verifies the parameters and reserved fields in their order in Table 4-7 on page 4-14, except it checks byte 0, bits 2 through 7 first. If the control unit detects an exception condition in more than one parameter in Table 4-7 on page 4-14, it reports only the first exception.
  • Page 53 Orientation Modifiers: Byte 0, Bits 0 and 1 contain orientation modifiers that specify the orientation to establish when the operation (bits 2 through 7) needs orientation to a specific record or record area before data transfer starts. Count Area ‘00’ – specifies that data access for the CCW immediately following the Locate Record command is to begin with the control unit oriented following the count field of the record that satisfied the search operation.
  • Page 54 Valid Operation Byte Values:: The following table shows the valid combinations of Orientation Modifiers and Operation Codes. All of the valid combinations are listed. Table 4-9. Locate Record Operation Byte Values Operation Code Orientation (Byte 0, Bits 2–7) (Byte 0, Bits 0–1) Data Orient Write Data...
  • Page 55 other code, the command is rejected with unit check status. The sense data contains command reject with format 0, message 4. Not Used – Byte 2 Byte 2 must contain zeros. If byte 2 does not contain zeros, the Locate Record command is rejected with unit check status.
  • Page 56 If the sector number is zero, the next command starts with the device in a position immediately before index. A value of X'FF' is valid and specifies that sector positioning is not to be performed before establishing orientation. Transfer Length Factor – Bytes 14 and 15 When the auxiliary byte, byte 1, bit 0, is a ‘1’, bytes 14 and 15 contain a transfer length factor.
  • Page 57 When operating with read intent, an incomplete Domain exception will not be reported. The Internal Disk Subsystem will threshold unit checks for Incomplete Domain exceptions. See “Nonsynchronous Operations” on page 4-19. Search Operation: Certain Locate Record operations need orientation to a specific record or record area before data transfer starts.
  • Page 58 data transfer to the disk subsystem. If the exception condition is related to the execution of a write command that had already presented clean ending status, sense data may also include imprecise ending (byte 1, bit 7). If an Incomplete Domain exception condition is detected after final status is presented for the last command in the chain and a subsequent exception condition prevents data from being successfully written to the logical volume, the next channel program to that logical volume will receive status that includes...
  • Page 59 The control unit uses the seek address and sector number parameters to start track access. When track access completes, the search operation specified by the search argument and the orientation modifiers (byte 0, bits 0 and 1) is performed. If the auxiliary byte bit 7 is ‘0’, the Locate Record command must be followed by the number of update write commands specified by the count parameter.
  • Page 60 If the record length is not zero, the operation is terminated with unit check status. Sense data will include Program Action Code ‘0F’. Format Write – ‘03’ Operation Code: This operation code prepares the control unit to format one or more consecutive user data records. The count parameter specifies the number of records to format.
  • Page 61 The control unit uses the seek address and sector number parameters to start track access. When track access is complete, the search operation specified by the search argument and the orientation modifiers (byte 0, bits 0 and 1) is performed. The Locate Record command must be followed by the number of read CCWs needed to process the number of records specified by the count parameter.
  • Page 62 The Locate Record command must be followed by one Write Data and a number of Write CKD commands that is one less than the value in the count parameter, with the following exceptions: An Erase command may be substituted for the last Write CKD command in the domain.
  • Page 63 After the last record on a track transfers, a pseudo count field of 8 bytes of X'FF' transfers to the channel. If the track has no records to transfer, the Read Tracks command sends only the pseudo count field. Note: The pseudo count field can be used to locate the end of the track image character string in the host system’s main storage.
  • Page 64 Only Read Count, Read Key and Data, Read Data, or Read Count Key and Data commands can follow a Read R0, Read Count, Read Key and Data, Read Data, or a Read Count Key and Data command. If a command in the Locate Record domain does not meet the sequence requirements, that command is rejected with unit check status.

  • Page 65: Locate Record Extended

    Locate Record Extended Hex Code Data Address Count The main storage location of the first parameter byte. 21 or Description: The location and number of records to process and the operation to perform are specified in the Locate Record Extended command parameters. See page 3-3 for how the Locate Record Extended command makes an operational domain.
  • Page 66 Other restrictions are described in the following text. Ending Status: The control unit presents channel end status after it verifies the parameters. If the operation uses cache, and the track and sector specified in the Locate Record Extended command is in cache, device end occurs with channel end.
  • Page 67 Orientation Modifiers: Byte 0, bits 0 and 1 contain orientation modifiers that specify the orientation to establish when the operation (bits 2 through 7) needs orientation to a specific record or record area before data transfer starts. Count Area ‘00’ – specifies that data access for the command immediately following the Locate Record Extended command begins with the control unit oriented following the count field of the record that satisfied the search operation.
  • Page 68 See "Locate Record Extended Operations" on page 4-26 for a description of the operation codes. Valid Operation Byte Values: The following table shows the valid combinations of Orientation Modifiers and Operation Codes. All of the valid combinations are listed. Table 4-13. Locate Record Extended Operation Byte Values Operation Code (Byte 0, Bits 2–7) Orientation Byte...
  • Page 69 Byte 1, Bit 7: When set to ‘1’, specifies that the last data transfer command in the Locate Record Extended domain will be a Read Count command. The Read Count command is a suffix to the Locate Record Extended domain. The record is included in the count of records processed as specified by the count parameter.
  • Page 70 Search Argument – Bytes 8–12 Bytes 8 through 12 specify the cylinder, head, and record (CCHHR). These bytes specify a value to be used as a search argument for the Locate Record Extended search operation. See “Search Operation” on page 4-19. When the operation (byte 0) does not need orientation to a specific record, no search operation occurs and bytes 8 through 12 are ignored.
  • Page 71 Extended Operation – Byte 17 Byte 17 contains an operation code unique to the Locate Record Extended command. When byte 0, bits 2–7 equal X'3F', byte 17 specifies the Locate Record Extended operation to be performed. If byte 0, bits 2–7 is not X'3F' the operation specified in byte 0, bits 2–7 is performed and byte 17 must be zero.
  • Page 72 Table 4-16. Extended Operation Code Length Extended Operation Codes Length Write Any (09) X'0001' Read Any (0A) X'0001' Read Trackset (0E) X'0001' X'0002' Prestage Trackset (10) X'0001' X'0002' Write Trackset (11) X'0001' X'0002' Update Write Trackset (13) X'0001' X'0002' Extended Parameter – Bytes 20–21 This is a variable length field.
  • Page 73 command is rejected with unit check status. The sense data contains command reject with format 0, message 4. Notes: 1. Extent checking is performed during the validation of Locate Record Extended parameters, not during track access. 2. The sector number parameter is not used. Track access is initiated using the seek address parameter.
  • Page 74 The extended parameter field must be one byte in length (byte 20 only). This byte specifies the set size used in the Locate Record Extended domain. The track set size must be ‘1’ (the device value returned in byte 47 of the Read Device Characteristics command response).
  • Page 75 If the number of records written is equal to the number of data records on the track, the count area read by a suffixed Read Count command is that of the first record that was updated. If the number of records written is not equal to the number of data records on the track, the count area read by a suffixed Read Count command will be that of the record that follows the last record updated.
  • Page 76 Each following Read Track command attempts to advance to the next specified track, orients to the home address, and transfers each count, key, and data area until end-of-track. A pseudo count field is transferred to the channel after the last record on a track is transferred.
  • Page 77 Write Trackset – ‘11’ Extended Operation Code: The Write Trackset Operation prepares the control unit to update the Record Zero data area and format write the user data records on one or more tracks. The tracks to be written are specified by the Extended Parameter and the number of tracks to be written is specified by the Count parameter.
  • Page 78 format 0, message 2, Invalid Command Sequence). An Invalid Command Sequence indication will be returned for any non-conforming command even if it is a command that is not executed by Internal Disk. For example, the Read Backward Command, ‘0C’, that is executed on tape devices and is never executed by Internal Disk, would encounter Invalid Command Sequence rather than Invalid Command in this instance.
  • Page 79 Disk, would encounter Invalid Command Sequence rather than Invalid Command in this instance. 4-41 Chapter 4. Command Descriptions...
  • Page 80 Prefix Hex Code Data Address Count The main storage location of the first Prefix Minimum of 64. parameter byte. Description: The Prefix command consolidates many commands that are used to convey information to the Internal Disk Subsystem. This command reduces the channel overheads associated with the transmission of multiple discrete commands.
  • Page 81 Format Byte: Table 4-17. Prefix, Byte 0, Format Bits Value Definition 0–7 Encoded Format Basic Prefix Command (includes Define Extent) Basic plus Locate Record Extended Parameters Basic plus PSF Command Parameters 03–FF Reserved. Must not be set for Internal Disk Field Validity Byte: Table 4-18.
  • Page 82 Basic Prefix Command Parameters - Format Byte x‘00’ The parameter list has the following format: Byte Parameter Format Flags Not used Auxiliary byte 4–11 Not used 12–43 Define Extent Parameters qualified by Byte 1, Bit 0. Mask byte Global Attributes 14–15 Blocksize in bytes 16–17 Ignored by Internal Disk Global Attributes Additional...
  • Page 83 Byte Parameter 62–63 Perform Subsystem Function Common Bytes Operation byte PSF Order PSF Flags 64–NN PSF Order unique parameters. NN is dependent on the order and can be 65535. 4-45 Chapter 4. Command Descriptions...

  • Page 84: Seek Operations

    Seek Operations When the control unit receives a Seek, Seek Cylinder, or Seek Head command, it validates the seek address parameter, determines if the track is in cache, and saves the parameters until it requires data access. Further activity is deferred as described in the following text.
  • Page 85 Seek Hex Code Data Address Count The main storage location of the seek address. Description: The Seek command transfers the track address to the control unit. The format of the seek address parameter is (00CCHH), where (00) is 2 bytes of binary zeros and (CCHH) is a 4-byte track address.

  • Page 86: Seek Cylinder

    Seek Cylinder Hex Code Data Address Count The main storage location of the seek address. Description: The Seek Cylinder command transfers the track address to the control unit. The format of the seek address parameter is (00CCHH), where (00) is 2 bytes of binary zeros and (CCHH) is a 4-byte track address.

  • Page 87: Seek Head

    Seek Head Hex Code Data Address Count The main storage location of the seek address. Description: The Seek Head command transfers the track address to the control unit. The format of the seek address parameter is (00CCHH), where (00) is 2 bytes of binary zeros and (CCHH) is a 4-byte track address.
  • Page 88 Recalibrate Hex Code Data Address Count The main storage location of the seek address. Description: The Recalibrate command causes the addressed logical volume to seek to cylinder 0, head 0. This command does not cause any data transfer. Therefore, if the CCW has a nonzero byte count, the suppress length indication (SLI) bit must be set to X'1' to avoid an incorrect length exception.

  • Page 89: Set File Mask

    Set File Mask Hex Code Data Address Count The main storage location of the file mask byte. Description: The Set File Mask command transfers a 1-byte mask to the control unit. A valid mask byte replaces the current value of the file mask. This command resets orientation in the control unit.

  • Page 90: Set Sector

    Set Sector Hex Code Data Address Count The main storage location of the sector byte. Description: This command resets orientation in the control unit. The Set Sector command transfers a 1-byte relative angular track position to the control unit. The sector number causes the logical volume to position to a specific sector before starting the next command.

  • Page 91: Read Sector

    Read Sector Hex Code Data Address Count The main storage location for the sector number. Description: This command resets track orientation in the control unit. The Read Sector command transfers a 1-byte sector number to the channel. The data byte represents the count-area sector position of the record that was operated on by the search or data transfer command that immediately precedes this command.

  • Page 92: Read Device Characteristics

    Read Device Characteristics Hex Code Data Address Count The main storage location for the first byte of device characteristics information. Description: The Read Device Characteristics command transfers 64 bytes to the channel. The information this command transfers defines the characteristics of the addressed logical volume.
  • Page 93 Table 4-20. Device Characteristics Data Bytes Contents 0–1 Subsystem type Subsystem model number and architecture 3–4 Device type Device model 6–9 Subsystem and device facilities Device class code Device type code 12–13 Number of primary cylinders 14–15 Tracks per cylinder Number of sectors 17–19 Track length...
  • Page 94 Byte 2: Identifies the subsystem model number and the supported architecture. The active bits show: Table 4-21. Byte 2 Definition Bits Value Definition 0–1 b'11' ECKD Architecture b‘1’ Nonsynchronous mode 3–4 b'00' Reserved 5–7 b'010' Control unit model Bytes 3 and 4: Contains the four-digit device type number as four hexadecimal digits.
  • Page 95 Table 4-22. Bytes 6–9 Definition Bytes Definition Bits Definition Multiple Burst ECC, set to one Subsystem supports the Read Track (0C) operation in a Locate Record domain, set to one Reserved, set to zero Subsystem supports the Read (16) operation in a Locate Record domain, set to one Subsystem supports Set System Characteristics (PSF Order Code x'1D'), set to one...
  • Page 96 Bytes 17 through 19: Contains an unsigned, 24-bit binary value that shows the total number of usable bytes on each track. This value is valid after the track has been formatted with a home address and a standard record zero (key length of 0 and data length of 8).
  • Page 97 Bytes 23 through 27: Contains factors, F1 through F5, to be used in the track capacity calculation formulas. See the description of byte 22 above. Bytes 28 and 29: Contains an unsigned, 16-bit binary value, which is the address (CC) of the first cylinder that contains alternate tracks. Bytes 30 and 31: Contains an unsigned, 16-bit binary value that shows the number of alternate tracks on the logical volume.
  • Page 98 The appropriate sector number for a Locate Record or a Set Sector command is the smallest integer equal to or less than the result of the following formula: Sector = (C0 + (2 X F7) + NetSpace) / (F1 X F8) Where: C0 is an unsigned 16-bit binary number contained in bytes 20 and 21.

  • Page 99: Read Commands

    Read Commands The read commands cause data to transfer from the cache to the channel. The control unit is oriented to a specific record area and sends one or more areas or records to the channel. All read commands except Read IPL must be preceded in the command chain by a command that specifies (or implies) (CCHH) parameters.

  • Page 100: Read Home Address

    Read Home Address Hex Code Data Address Count The main storage location of the Multitrack home address. Description: The Read Home Address command transfers a partial home address area to the channel. The control unit is oriented to index when the Read Home Address command starts.

  • Page 101: Read Record Zero

    Read Record Zero Hex Code Data Address Count The main storage location for the The number of count and Multitrack first byte of the record zero (R0) data bytes to be read. count data. Description: The Read Record Zero command transfers the entire record zero (count and data bytes) to the channel.

  • Page 102: Read Count, Key, And Data

    Read Count, Key, and Data Hex Code Data Address Count The main storage location for the The number of count, Multitrack first byte of the count data. key and data bytes to be read. Description: The Read Count, Key, and Data command transfers the entire count, key, and data areas of a record to the channel.
  • Page 103 Ending Status: The control unit presents channel end and device end status when data transfer completes. When the command completes, the control unit is oriented to the data area of the record that was read. 4-65 Chapter 4. Command Descriptions...

  • Page 104: Read Key And Data

    Read Key and Data Hex Code Data Address Count The main storage location for the The number of key and Multitrack first byte of the key data. data bytes to be read. Description: The Read Key and Data command transfers the key and data areas of a record to the channel.
  • Page 105 If the data length field in the count area contains zero, the control unit does not send any data area. The command is terminated with channel end, device end, and unit exception status. Ending Status: The control unit presents channel end and device end status when data transfer completes.

  • Page 106: Read Data

    Read Data Hex Code Data Address Count The main storage location for the The number of data Multitrack first byte of data. bytes to be read. Description: The Read Data command transfers the data area of a record to the channel.
  • Page 107 Ending Status: The control unit presents channel end and device end status when data transfer completes. When the command completes, the control unit is oriented to the data area of the record that was read. 4-69 Chapter 4. Command Descriptions...

  • Page 108: Read Count

    Read Count Hex Code Data Address Count The main storage location for the Multitrack first byte of the count area. Description: The Read Count command transfers the count area of a record, other than record zero, to the channel. The control unit is oriented to the next count area and sends that count area to the channel.

  • Page 109: Read Multiple Count, Key, And Data

    Read Multiple Count, Key, and Data Hex Code Data Address Count The main storage location for the At least as large as the maximum first byte of data. size record. Description: The Read Multiple Count, Key, and Data command transfers the next record (excluding R0) and all remaining records on the track to the channel.

  • Page 110: Read Track

    Read Track Hex Code Data Address Count The main storage location for the At least as large as the maximum first count area. size record, plus R0 length, plus 8 bytes. Description: The Read Track command transfers multiple records to the channel. This command is primarily for dump/restore utility programs.
  • Page 111 domain of a Read Tracks operation, the ‘next’ track is the track that is next in sequence. If the data area length is zero, the control unit neither sends the data area nor reports an exception status. The read operation continues with the next count area, if any, on the track.

  • Page 112: Read Track Data

    Read Track Data Hex Code Data Address Count The main storage location of the first byte to Number of bytes to be read. be read. Description: Read Track Data transfers multiple records from a track to the channel. Read Track Data is valid only in the domain of a Locate Record command that specified the Read Tracks operation code or a Locate Record Extended command that specifies Read Track, or a Read Trackset operation code.
  • Page 113 reached. If no user data area is detected on the next track, execution is terminated with status that includes unit check (No Record Found). Within the domain of a Read Tracks operation, the “next” track is the track that is next in sequence.

  • Page 114: Read Ipl

    Read IPL Hex Code Data Address Count The main storage location for the The number of data bytes to be first data byte. read. Description: The Read Initial Program Load (IPL) command causes the addressed logical volume to seek to cylinder 0, head 0. The logical volume then reads the data area of the record following R0.

  • Page 115: Search Commands

    Search Commands The search commands cause the control unit to be oriented to a specific record area on the track before the control unit processes a read or write command. The control unit gets the search argument from the channel and then reads a record area from the logical volume or cache.

  • Page 116: Search Home Address Equal

    Search Home Address Equal Hex Code Data Address Count The main storage location for the Multitrack cylinder number (CC) and the head number (HH). Description: The Search Home Address Equal command causes the control unit to request 4 bytes of home address data from the channel and compare that data to the 4 bytes of home address data read from cache or the logical volume.

  • Page 117: Search Id Equal

    Search ID Equal Hex Code Data Address Count The main storage location for the Multitrack record identifier; cylinder (CC), head number (HH), and record (R). Description: The Search Identifier (ID) Equal command causes the control unit to request a 5-byte record ID (CCHHR) from the channel and compare that data with the 5-byte count area ID read from cache.

  • Page 118: Search Id High

    Search ID High Hex Code Data Address Count The main storage location for the Multitrack record identifier; cylinder (CC), head number (HH), and record (R). Description: The Search ID High command operates the same as a Search ID Equal command, except that status modifier is included in ending status when the record ID compares high to the search argument.

  • Page 119: Search Key Equal

    Search Key Equal Hex Code Data Address Count The main storage location for the The length of the search Multitrack key to compare. argument. Description: The Search Key Equal command causes the control unit to compare a key data area received from the channel with the key data area read from cache. The KL field in the count area defines the length of the key area.

  • Page 120: Search Key High

    Search Key High Hex Code Data Address Count The main storage location for the The length of the search Multitrack key to compare. argument. Description: The Search Key High command operates the same as a Search Key Equal command except that status modifier is included in ending status when the key area compares high to the search argument.
  • Page 121 Write commands that do not operate in a Locate Record or Locate Record Extended domain must be preceded by a search command that compares equal on all bytes of the search field. The Locate Record Orient operation code does not satisfy the search prerequisite for a write command.

  • Page 122: Write Home Address

    Write Home Address Hex Code Data Address Count The main storage location of the home address. Description: The Write Home Address command simulates updating the home address record on the track, by verifying a 5-byte section of the home address record.

  • Page 123: Write Record Zero

    Write Record Zero Hex Code Data Address Count The main storage location of the R0 count, key and data bytes. Description: The Write Record Zero command formats a new record zero on the track. Record zero is always the first record following the home address area. The first 8 bytes of the record transferred from the channel are the count area: cylinder number (2 bytes), head number (2 bytes), record number (1 byte), key length (1 byte), and data length (2 bytes).

  • Page 124: Write Count, Key, And Data

    Write Count, Key, and Data Hex Code Data Address Count The main storage location of the count (8 The number of bytes to write. bytes), key and data bytes. Description: The Write Count, Key, and Data (CKD) command formats a new record on the track.
  • Page 125 Ending Status: If additional commands are expected within the domain of a Locate, device end will be presented with channel end. Otherwise channel end will be presented when the data transfer is complete to the cache. When the command completes, the control unit is oriented to the data area of the record just written. 4-87 Chapter 4.

  • Page 126: Write Count, Key, And Data Next Track

    Write Count, Key, and Data Next Track Hex Code Data Address Count The main storage location of the count (8 The number of bytes to write. bytes), key and data bytes. Description: The Write Count, Key, and Data (CKD) Next Track command formats the first user data record on the next track.
  • Page 127 Ending Status: If additional commands are expected within the domain of a Locate, device end will be presented with channel end. Otherwise channel end will be presented when the data transfer is complete to the cache. When the command is complete, the control unit is oriented to the data area of the record just written. 4-89 Chapter 4.
  • Page 128 Erase Hex Code Data Address Count The main storage location of the count, key, The number of count, key, and data bytes. and data bytes. Description: The Erase command erases one or more user data records from the track. The remaining portion of the track is erased starting from the end of the record written by the preceding Write R0 or Write CKD command, or from the end of the record that satisfied the Search ID Equal or Search Key Equal operation.

  • Page 129: Write Update Key And Data

    Write Update Key and Data Hex Code Data Address Count The main storage location of the data. The number of bytes to write. Description: The Write Update Key and Data command writes the key and data areas of an existing record. If the key length (KL) is zero, this command operates the same as a Write Update Data command.
  • Page 130 Chaining and Restrictions: Unit check status with the sense data containing command reject with format 0, message 2 occurs if: This command is not in a Locate Record or Locate Record Extended domain. This command is in a Locate Record or Locate Record Extended domain that did not specify a Write Data (01) operation code.

  • Page 131: Write Key And Data

    Write Key and Data Hex Code Data Address Count The main storage location of the data. The number of bytes to write. Description: The Write Key and Data command updates the key and data areas of an existing record. If the key length (KL) is zero, this command operates the same as a Write Data command.
  • Page 132 sense data containing command reject with format 0, message 2 occurs if this command is in the domain of a Locate Record that specifies any other operation. If the record has a data area length of zero and CKD Conversion mode is specified (Define Extent global attributes byte, bit 2 is a ‘1’), no data area transfer occurs.

  • Page 133: Write Update Data

    Write Update Data Hex Code Data Address Count The main storage location of the data. The number of bytes to write. Description: The Write Update Data command updates the data area of an existing record. The control unit writes data into the data area of the record. The amount of data is defined in the Locate Record transfer length factor parameter (or the Define Extent block size parameter if no transfer length factor was specified).
  • Page 134 status is presented when the write operation is completed at the logical volume. When the command completes, the control unit is oriented to the data area of the record just updated. 4-96 Internal Disk Subsystem Reference Guide...

  • Page 135: Write Data

    Write Data Hex Code Data Address Count The main storage location of the data. The number of bytes to write. Description: The Write Data command updates the data area of an existing record. Processing depends on whether this command is inside of or outside a Locate Record or Locate Record Extended domain.
  • Page 136 Outside the Domain of a Locate Record The control unit is oriented to a count or key area when the command starts (as the result of the preceding search command). It then writes the following data area. The data area length is defined in the data length (DL) field. If the channel sends fewer than (DL) bytes, binary zeros fill the remaining bytes of the data area.

  • Page 137: Write Full Track

    Write Full Track Hex Code Data Address Count The main storage location of the first Number of bytes to be transferred. parameter byte. Description: The Write Full Track command transfers data from the channel and writes the data on the track. Write Full Track is valid only in the domain of a Locate Record Extended command that specified the Write Trackset (11) Extended Operation code.
  • Page 138 channel to make this determination, execution is terminated with status that includes unit check (Command Reject, format 0, message 3, CCW byte count less than required). If it is the pseudo count field then the track image transfer is complete, the remainder of the track is erased. 2.
  • Page 139 ┌─────┬────┬─────┬────┬─────┬────┬ ┬─────┬────┬──────┐ │ R │ R │ R1 │ R1 │ R2 │ R2 │ │ Rn │ Rn │Pseudo│ │Count│Data│Count│Key+│Count│Key+│ │Count│Key+│Count │ │ │ │ │Data│ │Data│ │ │Data│ │ └─────┴────┴─────┴────┴─────┴────┴ ┴─────┴────┴──────┘ │ │ │ │ │ │ │ │8 bytes + │8 bytes + │8 bytes + │...

  • Page 140: Write Track Data

    Write Track Data Hex Code Data Address Count The main storage location of the first data byte Number of data bytes to be written. to be written. Description: The Write Track Data command transfers multiple records from the channel to a track. Write Track Data is valid only in the domain of a Locate Record Extended command that specifies an Update Write Trackset operation code.
  • Page 141 Ending Status: Channel end status is presented when data transfer from the channel is completed. If there are further tracks to be processed (more ‘1’ bits in the Extended Parameter), then device end status is included with channel end. After data transfer for the last track, device end status is presented when the write operation is completed at the logical volume.

  • Page 142: Sense Commands

    Sense Commands Sense commands send error information and specific device information to the channel. Sense Hex Code Data Address Count The main storage location for the first sense byte. Description: The Sense command sends 32 bytes of sense data from the control unit to the channel.

  • Page 143: Sense Id

    Sense ID Hex Code Data Address Count The main storage location for the first sense byte. Description: The Sense ID command sends 20 bytes of data describing the type and model number of the subsystem and logical volume to the channel. If the logical volume is not busy, the command will operate even if the logical volume is in the not-ready state (or absent).
  • Page 144 Table 4-26 (Page 2 of 2). Data Sent to Channel by Sense ID Command Bytes Description Value 16–19 Command Interface Word (CIW) for Read-Node-Identifier X'423E0040' 4-106 Internal Disk Subsystem Reference Guide...

  • Page 145: Miscellaneous Commands

    Miscellaneous Commands No-Operation Data Address Count Code Not checked for validity; should not exceed See the following text. addressing capacity. Description: The No-Operation command does not cause any data transfer. Therefore, if a nonzero byte count is specified in the command, the SLI bit must be set to ‘1’...

  • Page 146: Read And Reset Buffered Log

    Read and Reset Buffered Log Hex Code Data Address Count The main storage location for the first byte of usage information. Description: The Read and Reset Buffered Log command sends 32 bytes of data to the channel. This command is implemented for compatibility purposes only. A real 3990 control unit with 3380 and 3390 devices would report overflows of usage counters and other device usage statistics in device dependent formats.
  • Page 147 Table 4-27. Buffer Log data for 3390 Models Byte Contents 0–1 Reserved, set to zeros. Emulated Control Unit Type Code, set to the value in byte 42 of Read Device Characteristics data. Set to X'05'. Reserved, set to zero. Unit Address of the logical volume. Device type code of the real device.
  • Page 148 Table 4-28. Buffer Log Data for 3380 Models Byte Contents 0–1 Unused, set to zeros. Environmental data present. Set to X'10' Reserved, set to zero. Unit Address of the logical volume. 5–6 Unused, set to zeros. Format/Message Byte. Set to X'60' 8–11 Reserved for Bytes Read.

  • Page 149: Read Configuration Data

    Read Configuration Data Hex Code Data Address Count The main storage location for the configuration data. Description: The Read Configuration Data command sends 256 bytes of configuration data to the channel. This command shows the host how the Internal Disk Subsystem is configured. Also included are Part Numbers and Manufacturer IDs that the customer may use for inventory control applications.

  • Page 150: Configuration Data

    IDSK' 10-12 Model Number (EBCDIC); set to the Internal Disk subsystem model number which is (10-12) '002' 13-15 Manufacturer (EBCDIC); set to 'IBM' (13-15) 16-17 Manufacturing Plant Code(3) (EBCDIC) (16-17) 18-21 Sequence Number High (EBCDIC); this portion of the sequence number field is used (18-21) to hold the control unit number.
  • Page 151 IDSK' 42-44 Model Number (EBCDIC); set to the Internal Disk subsystem model number which is (10-12) '002' 45-47 Manufacturer (EBCDIC); set to 'IBM' (13-15) 48-49 Manufacturing Plant Code(3) (EBCDIC) (16-17) 50-53 Sequence Number High (EBCDIC); this portion of the sequence number field is used (18-21) to hold the control unit number.
  • Page 152 IDSK' 74-76 Model Number (EBCDIC); set to the Internal Disk subsystem model number which is (10-12) '002' 77-79 Manufacturer (EBCDIC); set to 'IBM' (13-15) 80-81 Manufacturing Plant Code(3) (EBCDIC) (16-17) 82-85 Sequence Number High (EBCDIC); this portion of the sequence number field is used (18-21) to hold the control unit number.
  • Page 153 Table 4-30 (Page 4 of 5). Internal Disk Configuration Data Byte(s)(1) Description 114-117 Sequence Number High (EBCDIC); this portion of the sequence number field is used (18-21) to hold the control unit number. These characters are in EBCDIC notation, representing four hexadecimal characters. This allows for up to X'FFFF' control units.
  • Page 154 Table 4-30 (Page 5 of 5). Internal Disk Configuration Data Byte(s)(1) Description Not used; set to x'00' (10) 235(5) Channel Connection Address; this is the unit address for this volume. (11) 236(5) Physical Device ID; this is the same as Channel Connection Address (byte 11 (12) above).
  • Page 155 ‘1’ to avoid an incorrect length exception. Note: Do not use this command when writing new applications. This command is provided only to maintain compatibility with other IBM disk devices. The Restore command resets orientation in the storage path. This command does not do any action at the logical volume, except to check logical volume status.

  • Page 156: Path Control Commands

    Path Control Commands Path control commands are primarily intended for environments where the disk data sets are shared among application programs. The sharing may be across two applications that are each running under different Operating Systems both of which are controlled by VM, or data sets may be shared between LPARs. Device Reserve Hex Code Data Address...
  • Page 157 Chaining and Restrictions: Unit check status with the sense data containing command reject with format 0, message 2 occurs if: This command is received in the domain of a Locate Record or Locate Record Extended command. This command was not the first command in the channel program or chained directly from a Suspend Multipath Reconnection command that was the first command in the chain.

  • Page 158: Device Release

    Device Release Hex Code Data Address Count The main storage location for the first sense byte. Description: The Device Release command transfers 32 bytes of sense data to the channel. If the logical volume is busy or reserved to another LPAR, the Device Release command is I/O queued.

  • Page 159: Unconditional Reserve

    Unconditional Reserve Hex Code Data Address Count The main storage location for the first sense byte. Description: The Unconditional Reserve command transfers 32 bytes of sense data to the channel. This command terminates the addressed logical volume’s allegiance or reservation to a channel path or path group, and establishes a device reservation to the channel path group of the channel sending the command.
  • Page 160 The channel had a reservation for this logical volume and did not have an active command chain. (Unit check will be pending to the next Start I/O.) The channel had a contingent allegiance for the logical volume, and sent a Sense command for that logical volume after the Unconditional Reserve command was received.

  • Page 161: Reset Allegiance

    Reset Allegiance Hex Code Data Address Count The main storage location for the first device status byte. Description: The Reset Allegiance command transfer 32 bytes of data to the channel. This command terminates a logical volume’s allegiance to a channel path or path group.
  • Page 162 Chaining and Restrictions: Unit check status with the sense data containing command reject with format 0, message 2 occurs if: This command is received in the domain of a Locate Record or Locate Record Extended command. This command is not the first command in the channel program or chained directly from a Suspend Multipath Reconnection command that was the first command in the chain.

  • Page 163: Set Path Group Id

    Set Path Group ID Hex Code Data Address Count The main storage location of the function control byte. Description: The Set Path Group ID command transfers 12 bytes to the control unit from the channel. The first byte is a function control byte and the following 11 bytes are the channel path group ID.
  • Page 164 Table 4-32. Set Path Group ID Byte 0 Definition Byte 0 Value Description Bits Single-Path Mode Multipath Mode is Not Supported 1–2 Establish Group Disband Group Resign from Group Reserved, must not be set 3–7 00000 Reserved, must be zeros Single-Path Mode: I/O operations must be maintained for the specific channel path over which the start I/O was initiated.
  • Page 165 When a mode bit is established for a path group, a following mode bit is not the same. The function control byte bits 1 and 2 are ‘11’. Bits 3 through 7 of the function control byte are not zeros. Ending Status: The control unit presents channel end and device end after it validates the parameters.

  • Page 166: Sense Path Group Id

    Sense Path Group ID Hex Code Data Address Count The main storage location for the first byte of path group identification. Description: The Sense Path Group ID command transfers 12 bytes of path group data to the channel. The 12 data bytes are a portion of the addressed logical volume’s path group data associated with the channel path where this command is executed.
  • Page 167 Chaining and Restrictions: Unit check status with the sense data containing command reject with format 0, message 2 occurs if this command: Is in the domain of a Locate Record or Locate Record Extended. Is not the only command in the channel program or chained directly from a suspend multipath reconnection that was the first command in the channel program.

  • Page 168: Suspend Multipath Reconnection

    Suspend Multipath Reconnection Hex Code Data Address Count Ignored. See the description. Description: The Suspend Multipath Reconnection command does not cause any data transfer. Therefore, if a nonzero byte count is specified in the command, the SLI bit must be set to ‘1’ to avoid an incorrect length exception. This command is for recovery operations in multipath mode.
  • Page 169 Table 4-34. Perform Subsystem Function Orders and Flags Byte Description Order Byte Name of Order Value 00–17 Reserved Prepare for Read Subsystem Data 19–1A Reserved Set Special Intercept Condition Reserved Set System Characteristics 1E–AF Reserved Set Interface Identifier B1–FF Reserved Flag Byte Bits Description Must be set to zero.
  • Page 170 Table 4-35. Parameter Bytes for Prepare for Read Subsystem Data X'18' Bytes Definition Flag byte. Must be set to zero 2–5 Reserved Suborder defining the data to place in the buffer: Value Description of the suborder The status of the subsystem. Cache performance statistics.
  • Page 171 are called "global" commands. Set Special Intercept Condition causes global commands to be rejected. Internal Disk has only two of the global commands that this order is designed to intercept. When the host operating system has conditioned a logical volume with this order, the commands that Internal Disk intercepts and rejects are: Perform Subsystem Function with Set System Characteristics Order Another Perform Subsystem Function with Set Special Intercept Order...
  • Page 172 Sense Subsystem Status (Page 4-136) The exchange of information about host and subsystem support of commands and op codes does not alter the execution of the commands and op codes. If a host denies support of the Prefix command (Byte 6, bit 0 set to zero) and later issues the Prefix command, Internal Disk will execute the command.
  • Page 173 No validity checks are made on parameter bytes 2–65. The subsystem will ignore any bits set that it does not understand. This information is retained by the subsystem as long as the path group is valid. Set Interface Identifier X'B0' The Set Interface Identifier order can set an interface identifier for the addressed logical volume and prepares node identifier information to be read by a Read Subsystem Data command chained from this Perform Subsystem Function...

  • Page 174: Sense Subsystem Status

    rejected with unit check status. The sense data contains command reject with format 0, message 2. Ending Status: When the parameters have been validated, channel end and device end are presented. Sense Subsystem Status Hex Code Data Address Count The main storage location for the first byte of status. The Sense Subsystem Status command causes the Internal Disk to send 40 bytes of information to the channel describing the status of the Internal Disk and the addressed logical volume.
  • Page 175 Table 4-38. Sense Subsystem Status Return Data Bytes Value Description x'00' Format zero is the only format supported by Internal Disk x'aa' Logical Volume Address x'nn' Number of Logical Volumes with Statistics x'01' Number of Statistics Sets per Logical Volume x'00' Overall caching status, set to zeros x'00'...
  • Page 176 Byte 14 – 17, Available Cache Capacity in Bytes: This field contains the same value as that in Bytes 10 – 13. Byte 26, Internal Disk Fast Write Status: Bits 0-1 are reserved and set to zeros. Bits 2 and 3 are used to reflect the state of Internal Disk RAID Fast Write (IDRFW) for the logical volume.

  • Page 177: Read Subsystem Data

    Read Subsystem Data Hex Code Data Address Count The main storage location for the Number of bytes the Perform data. Subsystem Function command requests. The Read Subsystem Data command causes the Internal Disk to send the data requested by the Perform Subsystem Function command, from which the Read Subsystem Data command is chained.
  • Page 178 Storage Subsystem Status Prepare for Read Subsystem Data with byte 6 equal to X'00', a 16-byte record is returned which consists of the first byte set to '48'x and the remaining bytes set to zeros. The 3990-2 returns storage path status in these bytes. Table 4-40 shows the contents of the record returned by Internal Disk.
  • Page 179 Table 4-41 (Page 2 of 2). Performance Statistics Bytes Description 32–35 Write sequential I/O operation hits. The number of sequential operations that had at least one write command but did not cause any portion of a track to be staged from the disk subsystem to cache. 36–51 Reserved, for Cache Fast Write Statistics.
  • Page 180 Type Number (EBCDIC); set to the Internal Disk Subsystem type number which is "IDSK" 10-12 Model Number (EBCDIC); set to the Internal Disk Subsystem model number which is "002" 13-15 Manufacturer (EBCDIC); set to IBM 16-17 Manufacturing Plant Code (EBCDIC) 18-21 Host Machine Type (EBCDIC); set to '7060' 22-29 Sequence Number Low (EBCDIC);...
  • Page 181 Table 4-43 (Page 2 of 2). Node Descriptor Format Byte Description Flags Bit Description 0-2 Node Qualifier Contents, set to b'000' meaning: The Node-Qualifier field contains a list of interface IDs. Because Internal Disk has only one CHPID, the list has a single entry that points back to the only valid CHPID. 3-7 Reserved, set to zeros.
  • Page 182 4-144 Internal Disk Subsystem Reference Guide...

  • Page 183: Chapter 5. 24-Byte Compatibility Sense Data

    The Internal Disk detects some error conditions when not communicating with a channel, or after it presents ending status for a CCW chain. The Internal Disk does not report the error until the next channel-initiated selection. Predicted device failures are reported in this manner.  Copyright IBM Corp. 1999...

  • Page 184: Byte Sense Data Summary

    24-Byte Sense Data Summary The Internal Disk sense data is presented to the CPU as 24-byte compatibility sense when byte 27, bit 0, is set to ‘1’. Table 5-2 on page 5-3 contains a summary of the 24-byte compatibility sense data.
  • Page 185 Table 5-2. Sense Information Summary–24-Byte Compatibility Byte Bits Meaning Page Command Reject Intervention Required Reserved, set to zero Equipment Check Data Check 5–6 Reserved, set to zero Incomplete Domain Permanent Error Invalid Track Format End-of-Cylinder Message to Operator No Record Found File Protected Reserved, set to zero Imprecise Ending...

  • Page 186: Byte Sense Data Description

    24-Byte Sense Data Description When byte 27, bit 0 is ‘1’, the sense data uses 24-byte compatibility mode. Bytes 0 through 7 and 24 through 31 are common to all formats in 24-byte compatibility sense. Bytes 8 through 23 depend on the format in bits 0 through 3 of byte 7. Sense Bytes 0, 1, and 2 The Internal Disk generates sense bytes 0 through 2 when it presents a unit check.
  • Page 187 Note: When an incomplete domain exception occurs, it may prevent the unit check for a subsequent exception from being presented with ending status. Byte 1, Bit 0–Permanent Error: A modifier bit that overrides any other possible bit settings. When set to ‘1’, this bit shows that host program error recovery procedures (ERPs) are not required.

  • Page 188: Sense Byte 3–Count

    3. In the domain of a Locate Record or Locate Record Extended, either R0 or a user record could not be found after a head or cylinder switch. Byte 1, Bit 5–File Protected: Can be caused by a programming error or an expected programming condition.

  • Page 189: Sense Byte 5–Low Cylinder Address

    Bits 2-7 contain the logical volume address. Sense Byte 5–Low Cylinder Address Represents the least significant bits of the last cylinder argument acted upon at this logical volume. For a 3390/9 logical volume, the cylinder and head address can not be contained in two bytes.
  • Page 190 A long busy condition exists in the subsystem or logical volume. Environmental-data present (byte 2, bit 3) is a ‘1’ and byte 7 contains X'F0'. A command was rejected because the interface was disabled for specific commands by the Set Special Intercept Condition order of the Perform Subsystem Function command.
  • Page 191 Table 5-5 (Page 2 of 2). Sense Bytes 29 through 31 Byte Bits Content Cylinder 128 Cylinder 64 Cylinder 32 Cylinder 16 Cylinder 8 Cylinder 4 Cylinder 2 Cylinder 1 0–3 Reserved Head 8 Head 4 Head 2 Head 1 Chapter 5.

  • Page 192: Byte Compatibility Sense Data Formats

    24-Byte Compatibility Sense Data Formats Format 0–Program or System Checks This format reports program or system check conditions. Sense Bytes 8 through 23 for Format 0 Format 0 sense bytes 8 through 23 contain the following: Table 5-6. Sense Bytes 8–23 – Format 0 Bytes Definition The reason code for some messages;...

  • Page 193: Format 1–Device Equipment Checks

    Message 9–E: Reserved. Message F–Status Not As Required: Occurs when one of the following byte 8 Reason Codes is specified. Code Reason No message. 01–28 Reserved. Trying to do a Perform Subsystem Function command with the Set Special Intercept Condition order on an interface on which no path group has been established.
  • Page 194 Microcode detected data discrepancy, message 3 Intervention required, message 9, due to: 1. Not physically attached to Internal Disk 2. Not available for use because the drive motor is off or is powering on. 3. The HDD has been disabled via the Service Element. 4.

  • Page 195: Format 2–Internal Disk Control Unit Errors

    Table 5-8. Format 1 Messages Byte 7 Format 1 Message Symptom Bits 4-7 Code Value Device fails to respond 'E000'X Predictive failure analysis 'E101'X Reserved – Microcode detected data discrepancy. 'E300'X Reserved – Intervention Required 'E210'X Reserved – Format 2–Internal Disk Control Unit Errors Format 2 is for a Internal Disk control unit errors.

  • Page 196: Format 4–Unrecovered Data Checks

    Sense Bytes 8 through 23 for Format 3 Format 3 sense bytes 8 through 23 contain the following: Table 5-11. Sense Bytes 8–23 – Format 3 Bytes Definition 8–10 Reserved, Set to zeros 11–12 Hardware level ID for field-replaceable unit. 13–14 Reserved, set to zeros.

  • Page 197: Format 5 To Format E – Not Used

    Format 5 to Format E – Not used Format F–Subsystem Checks Two messages are used under format F to report: Long busy condition using message 0. (Defective sector reassignment is an example.) Inability to determine the Internal Disk RAID Fast Write status of a logical volume using message C.
  • Page 198 5-16 Internal Disk Subsystem Reference Guide...

  • Page 199: Chapter 6. Eckd 32-Byte Sense Data

    The Internal Disk detects some error conditions when not communicating with a channel, or after it presents ending status for a CCW chain. The Internal Disk does not report the error until the next channel-initiated selection. Predicted device failures are reported in this manner.  Copyright IBM Corp. 1999...

  • Page 200: Eckd 32-Byte Sense Data Summary

    ECKD 32-Byte Sense Data Summary The Internal Disk sense data is presented to the CPU as ECKD 32-byte sense when byte 27, bit 0, is ‘0’. Byte 6 contains the content and format of the other bytes. The contents of bytes 7 through 14 are dependent on the Exception Class in bits 0–3 of byte 22 and the format in bits 4–7 of byte 6.
  • Page 201 Table 6-2. ECKD 32-Byte Sense Data Summary Byte Bits Meaning Page Command Reject Intervention Required Reserved Equipment Check Data Check 5–6 Reserved Incomplete Domain Permanent Error Invalid Track Format Reserved, set to zero Message to operator Reserved, set to zero File Protected Reserved, set to zero Imprecise Ending...

  • Page 202: Eckd 32-Byte Sense Data Description

    ECKD 32-Byte Sense Data Description When byte 27, bit 0 is ‘0’, the sense data uses 32-byte mode. Sense Byte 0 Byte 0, Bit 0–Command Reject: Occurs for any of the following conditions. (Sense byte 7 identifies the error condition in more specific terms.) 1.

  • Page 203: Sense Byte 2–Control Unit Type

    Byte 1, Bit 1–Invalid Track Format: Indicates that an invalid track condition is set for the following: 1. An update write operation is attempted on a record whose size differs from the record size parameter (TLF). 2. An attempt is made to exceed the track capacity of the track. 3.

  • Page 204: Sense Byte 5–Device Type Code

    Sense Byte 5–Device Type Code For exception classes 4 and E this byte contains a code that defines the device type and model. For 9GB Ultrastar2 XP drives on the Internal Disk Subsystem, the code is X'3B'. This code is the same as byte 57 of the data returned by the Read Device Characteristics command (see page 4-54).

  • Page 205: Sense Byte 24–Logging And Message Control

    Sense Byte 24–Logging and Message Control The definitions in byte 24 are: Table 6-4. Byte 24 – 32-Byte Sense Bits Definition 0–3 Reserved 4–5 Logging action 6–7 Operator message control Bits 4 and 5–Logging Action: These bits show the error recovery procedure (ERP) how to log this error.

  • Page 206: Sense Byte 28–Message Code

    message action. A program is not required to interpret additional sense data to determine if an operator message is required. When bits 6–7 are ‘10’, a message to the operator is to be sent once within a retry sequence on a path whether or not the retry action is successful. When bits 6–7 are ‘11’, a message is sent to the operator only if the error condition persists through all retry actions on a path.

  • Page 207: Sense Bytes 29 And 30–Cylinder Address

    Sense Bytes 29 and 30–Cylinder Address If byte 6, bit 2 is ‘1’, these bytes contain a valid value. For exception classes 4 and E, these bytes contain the cylinder address of the most recent seek argument accepted from the channel or executed by an internal operation. Table 6-9.

  • Page 208: Sense Data Dependent On Exception Class

    Sense Data Dependent on Exception Class Bits 0–3 of byte 22 contain the exception class for ECKD 32-byte sense data. Bits 4–7 of byte 22 describe the category of exceptions. Byte 6, bits 4–7, define the format of the data in bytes 7–19 for each exception class.
  • Page 209 Table 6-11. Exception Class 0 – Format 2. (Byte 6, bits 4–7 set to X'2'.) Byte Contents Count Byte Contains the number of records or tracks remaining to be transferred. 7–9 Values received in the locate record parameters Byte Definition Operation Byte (byte 0) Auxiliary Byte (byte 1) Reserved Byte (byte 2)
  • Page 210 Table 6-12 (Page 2 of 2). Exception Class 0 – Format 4. (Byte 6, bits 4–7 set to X'4'.) Byte Contents Operation Byte (byte 0) Contains the Operation Byte (byte 0) of the Locate Record or Locate Record Extended command that established the domain. Contains the Extended Operation code from byte 17 when the domain was established by a Locate Record Extended command.
  • Page 211 Table 6-13. Exception Class 4 – Format 1. (Byte 6, bits 4–7 set to X'1'.) Byte Contents 7–19 Unused, set to zero 20–21 SSID Exception Class and Category. Set to '44'x. Exception Condition. Set to 'C0'x. Indicating permanent error, not recovered. Bits Description Reserved...
  • Page 212 Table 6-15. Exception Class E – Category 1, Bytes 6 – 25 Byte Contents x'C2' Content and Format 7–19 Reserved, set to zero. 20–21 Subsystem ID (SSID) X'E1' Exception Class and Type Set to zero. X'08' Log once X'10' Asynchronous message Category 2–Intervention Required: Shows that the addressed logical volume is in one of the following states: 1.
  • Page 213 Table 6-17. Exception Class E – Category 3, Bytes 6 – 25 Byte Contents x'E1' Content and Format 7–19 Reserved, set to zero. 20–21 Subsystem ID (SSID) X'E3' Exception Class and Type Set to zero. X'0A' Log and message once X'83' Retry CCW chain and do 255 retries.
  • Page 214 6-16 Internal Disk Subsystem Reference Guide...

  • Page 215: Chapter 7. Error Recovery Procedures

    Present Data Check Unrecoverable Data Check Permanent Error Invalid Track Format Track capacity exceeded. (1) The sense data is not logged if the Format (byte 7, bits 0–3) is ‘0’ or ‘F’.  Copyright IBM Corp. 1999...

  • Page 216: Error Recovery Actions

    Table 7-1 (Page 2 of 2). Error Conditions Byte Sense Data Condition End-of-Cylinder End-of-cylinder during a multitrack operation outside the domain of a Locate Record or Locate Record Extended. Environmental-Data Attention was presented on an interface disabled by Present (with format the Perform Subsystem Function command with the 0, message F) Set Special Intercept Condition order.
  • Page 217 Action 5: 1. If the chain has not been retried 10 times, repeat the command chain. 2. Do Action 1. Action 6 Not used. Action 7: 1. Increment the cylinder address of the seek argument in sense bytes 5 and 6 (or 29 and 30) by one.
  • Page 218 Seek Argument from step 2a Set File Same as original Mask The first non-TIC CCW following the interrupted CCW. d. Continue the operation with the following CCW chain: Seek Argument from step 2a on page 7-3 Define The user’s new extent is compatible with the seek argument from step Extent 2a on page 7-3.

  • Page 219: Error Message

    Define Extent The user’s new extent is compatible with the seek argument from steps 4a and 4b. The other parameters are the same as the original parameters. Locate Bytes Contents Record Same as in original Locate Record command, except: If sense byte 3 equals ‘01’ and the original Locate Record command byte 1, bit 7 was ‘1’, then set byte 0, bits 2–7 to equal ‘16’...

  • Page 220: Erp Actions

    ERP Actions Error recovery program actions are indicated by the contents of sense byte 25. Byte 25 contains either a single or a compound program action code. If bit 0 of byte 25 is ‘0’, bits 1–7 contain a single program action code that identifies a recovery action for one specific condition.
  • Page 221 program must obtain this data from the original command within processor storage since this information is not available in the sense data. Error recovery programs may be unable to find the original Locate Record Extended command when the command follows a part of a channel program which contains conditional branching (via status modifier).
  • Page 222 Action 15: A multitrack data transfer operation within the domain of a Locate Record or Locate Record Extended command has attempted to switch to a new track and the next track is outside the defined extent. Sense bytes 29–31 contain the address ‘CCH’ of the last track operated upon. Recovery steps: 1.

  • Page 223: Erp Message Requirements

    the original Locate Record cannot be found, then exit with a permanent error indicator. Sense bytes 29–31 contain the address ‘CCH’ of the track where the channel program restarts. Recovery steps: 1. Determine the address of the CCW to be restarted using the count of the completed operations and the command address in the channel status information.
  • Page 224 message code (byte 28) defines. The operator message control can specify messages to be sent unconditionally, sent once during an ERP sequence, or sent if the procedure is unsuccessful. (See “Sense Byte 24–Logging and Message Control” on page 6-7.) 7-10 Internal Disk Subsystem Reference Guide...

  • Page 225: Appendix A. Device Characteristics

    Table A-5 on page A-9 "3380 Device Geometry and Characteristics" — Shows expansions of the device characteristics data. Table A-6 on page A-9 "3380 Access Authorization Address Range" — Shows the track addresses that may be reached with Normal or Device Support Authorization.  Copyright IBM Corp. 1999...
  • Page 226 Table A-1 (Page 1 of 3). 3390 Model 1/2/3/9 Device Characteristics Bytes Description Emulated 3390 0–1 Subsystem type x‘3990’ Subsystem Model x‘E2’ and Architecture 3–4 Device type x‘3390’ Device model 3390-1 x‘02’ 3390-2 x‘06’ 3390-3 x‘OA’ 3390-9 x‘0C’ Subsystem and device facilities Bits Definition...
  • Page 227 Table A-1 (Page 2 of 3). 3390 Model 1/2/3/9 Device Characteristics Bytes Description Emulated 3390 Device type code 3390-1 x‘26’ 3390-2 x‘27’ 3390-3 x‘24’ 3390-9 x‘32’ 12–13 Primary cylinders 3390-1 1113 Cyl x‘0459’ 3390-2 2226 Cyl x‘08B2’ 3390-3 3339 Cyl x‘0D0B’...
  • Page 228 Table A-1 (Page 3 of 3). 3390 Model 1/2/3/9 Device Characteristics Bytes Description Emulated 3390 Device and Control Unit Features Bits Definition Reserved b‘0’ RAID Device b‘1’ Reserved b‘0’ Transparent Subsystem Cache b‘1’ 4–7 Reserved b‘0000’ Reserved x‘00’ Real Control Unit Type Code x‘1E’...
  • Page 229 Table A-3. 3390 Models 1/2/3/9 Access Authorization Address Range Description Emulated 3390 Normal Access x‘00000000’ High 3390-1 1113 Cyl x‘0458000E’ 3390-2 2226 Cyl x‘08B1000E’ 3390-3 3339 Cyl x‘0D0A000E’ 3390-9 10017 Cyl x‘2720000E’ Device Support x‘00000000’ High 3390-1 1113 Cyl x‘0458000E’ 3390-2 2226 Cyl x‘08B1000E’...
  • Page 230 Table A-4 (Page 1 of 3). 3380 Models J/E/K Device Characteristics Bytes Description Emulated 3380 0–1 Subsystem type x‘3990’ Subsystem Model x‘E2’ and Architecture 3–4 Device type x‘3380’ Device model 3380-J x‘16’ 3380-E x‘0A’ 3380-K x‘1E’ Subsystem and device facilities Bits Definition Multiple Burst ECC...
  • Page 231 Table A-4 (Page 2 of 3). 3380 Models J/E/K Device Characteristics Bytes Description Emulated 3380 12–13 Primary cylinders 3380-J 885 Cyl x‘0375’ 3380-E 1770 Cyl x‘06EA’ 3380-K 2655 Cyl x‘0A5F’ 14–15 Tracks per cylinder x‘000F’ Number of sectors x‘DE’ 17–19 Track length x‘00BB60’...
  • Page 232 Table A-4 (Page 3 of 3). 3380 Models J/E/K Device Characteristics Bytes Description Emulated 3380 58–63 Reserved Zeros Note: * Internal Disk supports this function, however, this bit will only be set if the system has also indicated support of the function in a prior command. See "Set System Characteristics - PSF Order Code x'1D' on page 4-129.
  • Page 233 Table A-6. 3380 Models J/E/K Volumes Access Authorization Address Range Description Emulated 3380 Normal Access x‘00000000’ High 3380-J 885 Cyl x‘0374000E’ 3380-E 1770 Cyl x‘06E9000E’ 3380-K 2655 Cyl x‘0A5E000E’ Device Support x‘00000000’ High 3380-J 885 Cyl x‘0374000E’ 3380-E 1770 Cyl x‘06E9000E’...
  • Page 234 A-10 Internal Disk Subsystem Reference Guide...

  • Page 235: Appendix B. Caching Algorithms

    Do not keep a cache image of the written data. Write - Keys on the track and Write Data or format write with Search Key  Copyright IBM Corp. 1999...

  • Page 236: Algorithms For Cache Hits

    If the reference is to the front of a partial track image, stage the track from the point of reference up to the start of the partial track image and treat the operation as a hit. If the reference is to HA or R0 of the track, stage the track from index to the end of data.

  • Page 237: Algorithm Special Cases

    – Write Miss Execute the channel program using the cache and write the data to the disk subsystem. Invalidate copy of the track in the cache. – Write Hit Invalidate copy of the track in the cache. Read the data into the cache and execute the channel program using this cache image and write the data to the disk subsystem.
  • Page 238 Internal Disk Subsystem Reference Guide...

  • Page 239: Appendix C. Warranties

    The warranties provided by IBM in this Statement of Limited Warranty apply only to Machines you originally purchase for your use, and not for resale, from IBM or an IBM authorized reseller. The term “Machine” means an IBM machine, its features, conversions, upgrades, elements, or accessories, or any combination of them.
  • Page 240 (called “On-site”) or at one of IBM's or a reseller's service locations (called “Carry-in”) or 2) an “Exchange” service, either On-site or Carry-in. When a type of service involves the exchange of a Machine or part, the item IBM or your reseller replaces becomes its property and the replacement becomes yours.
  • Page 241 IBM. In each such instance, regardless of the basis on which you are entitled to claim damages, IBM is liable only for: 1. bodily injury (including death), and damage to real property and tangible personal property;...

  • Page 242: Ibm Agreement For Licensed Internal Code

    (“IBM”) owns copyrights in Code. IBM owns all copies of Code, including all copies made from them. If you are the rightful possessor of a Specific Machine, IBM grants you a license to use the Code (or any replacement IBM provides) on, or in conjunction with, only the Specific Machine for which the Code is provided.
  • Page 243 4. lease the Code or any copy of it. Appendix C. Warranties...
  • Page 244 Internal Disk Subsystem Reference Guide...

  • Page 245: Appendix D. Notices

    Web sites. The materials at those Web sites are not part of the materials for this IBM product and use of those Web sites is at your own risk. IBM may use or distribute any of the information you supply in any way it believes appropriate without incurring any obligation to you.

  • Page 246: Electronic Emission Notices

    Other company, product, and service names may be trademarks or service marks of others. Electronic Emission Notices The following statement applies to this IBM product. The statement for other IBM products intended for use with this product will appear in their accompanying manuals.
  • Page 247 Department of Communications. Operation in a residential area may cause unacceptable interference to radio and TV reception requiring the owner or operator to take whatever steps are necessary to correct the interference. Avis de conformlté aux normes du ministère des Communications du Canada Cet équipement ne dépasse pas les limites de Classe A d'émission de bruits radioélectriques pour les appareils numériques, telles que prescrites par le Règlement sur le brouillage radioélectrique établi par le ministère des...
  • Page 248 Internal Disk Subsystem Reference Guide...

  • Page 249: List Of Abbreviations

    Data Facility Sort key length Data length KSDS Key-sequenced data set EBCDIC Extended binary coded decimal kilovolt ampere interchange code Logical control unit EMIF ESCON Multiple Image Facility Linear data set End-of-file Least recently used algorithm  Copyright IBM Corp. 1999...
  • Page 250 Maintenance analysis procedure System Management Facilities Megabyte MVS Storage Management Library Most recently used Storage Management Subsystem MVSCP MVS configuration program SSID Subsystem identifier Operating system Triple Capacity Option Partitioned access method Transaction Processing Facility Program function keyboard Time sharing option PLPA Pageable link pack area Track record...
  • Page 251 A hardware unit that controls the terms used in this book. This glossary includes reading, writing, or displaying of data at one or more definitions from the IBM Dictionary of Computing, input/output devices. See also storage control. McGraw-Hill, New York (1994) count-key-data (CKD).
  • Page 252 Enterprise Systems Connections (ESCON). A set of IBM products and services that provide a dynamically connected environment within an enterprise. environmental-data. Data the control unit must report media. The disk surface on which data is stored.
  • Page 253 software transparency. For the Internal Disk products, a logical emulation with the actual hardware being transparent to the host system. predictive failure analysis. Failure analysis techniques that predict errors before they actually occur. SIM Alert message. An operator console message that notifies the operator that a SIM has been generated primary track.
  • Page 254 Internal Disk Subsystem Reference Guide...
  • Page 255 Seek Head 4-49 inhibit loading 4-11 Sense 4-104 modes 4-11 Sense ID 4-105 CCW count less than required 5-10 Sense Path Group ID 4-128 CCW description 4-1 Sense Subsystem Status 4-136 Set File Mask 4-51  Copyright IBM Corp. 1999...
  • Page 256 command (continued) device (continued) descriptions (continued) pending status 2-4 Set Path Group ID 4-125 status, effect on command 2-5 Set Sector 4-52 Device Release command 4-120 Suspend Multipath Reconnection 4-130 Device Reserve command 4-118 Unconditional Reserve 4-121 device support Write CKD 4-86 authorization 4-10 Write CKD Next Track 4-88 diagnostic...
  • Page 257 exception (continued) invalid (continued) classes, sense data 6-10 command sequence 5-10 code, sense byte 6-6 parameter 5-10 conditions 4-2 track Format, sense byte 5-5 extent beginning of 4-13 definition 3-3 key length 4-64, 4-85, 4-86 end of address 4-13 See key length file mask, description 3-4 Locate Record...
  • Page 258 logging and message control, sense byte 6-7 padding, write 4-83 logging mode, cache 4-12 parameters long busy 1-7, 5-15, 7-2 Define Extent 4-8 — 4-13 invalid, message 5-10 Locate Record 4-14 — 4-18 pending status mask causes 2-4 byte, Define Extent command 4-8 conditions 2-4 description 3-4 logical volume 2-4...
  • Page 259 Read Track command 4-72 Seek command 4-47 Read Tracks, Locate Record operation 4-24 Seek Cylinder command 4-48 Read Trackset, Locate Record Extended Seek Head command 4-49 operation 4-37 Seek Operations command 4-46 Read, Locate Record operation 4-25 selective reset 2-10 Recalibrate command 4-50 sense record...
  • Page 260 status (continued) Write Home Address command 4-84 initial 2-4 Write Key and Data command 4-93 modifier 2-2 Write Record Zero command 4-85 not as required 5-11 Write Track, Locate Record operation 4-23 pending 2-4 Write Trackset, Locate Record Extended presentation 2-1 operation 4-39 presented to commands, summary 2-5 Write Update Data command 4-95...
  • Page 261 No postage stamp necessary if mailed in the U.S.A. (Elsewhere, an IBM office or representative will be happy to forward your comments or you may mail directly to the address in the Edition Notice on the back of the front cover or title page.)
  • Page 262 Cut or Fold Readers' Comments — We'd Like to Hear from You Along Line SA22-1025-00  Fold and Tape Please do not staple Fold and Tape NO POSTAGE NECESSARY IF MAILED IN THE UNITED STATES BUSINESS REPLY MAIL FIRST-CLASS MAIL PERMIT NO. 40 ARMONK, NEW YORK POSTAGE WILL BE PAID BY ADDRESSEE International Business Machines Corporation Information Development...
  • Page 264  Printed in the United States of America on recycled paper containing 10% recovered post-consumer fiber. SA22-1 25-...

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