Page 1: Installation Guide
PCI RAID Controller Installation Guide DAC960PG PCI to Ultra-SCSI P/N: 771971-D01...
Page 3 Part Number 771971-D01 © Copyright 1997 Mylex Corporation. All Rights Reserved. All contents of this manual are copyrighted by Mylex Corporation. The information contained herein is the exclusive property of Mylex Corporation and shall not be copied, transferred, photocopied, translated on paper, film, electronic media, or computer-readable form;...
Page 4 (even if Mylex Corporation has been advised of the possibility of such damages). Any questions or comments regarding this document or its contents should be addressed to Mylex Corporation at the address shown on the cover.
Page 5 Class B Compliance THIS DEVICE COMPLIES WITH PART 15 OF THE FCC RULES. OPERATION IS SUBJECT TO THE FOLLOWING TWO CONDITIONS: 1. THIS DEVICE MAY NOT CAUSE HARMFUL INTERFERENCE, AND 2. THIS DEVICE MUST ACCEPT ANY INTERFERENCE RECEIVED, INCLUDING INTERFERENCE THAT MAY CAUSE UNDESIRED OPERATION.
Page 6: Declaration Of Conformity
Manufacturer’s Address: 34551 Ardenwood Blvd. Fremont, CA94555-3607 Declares that the product: Product Name: 1, 2, and 3 Channel RAID Controller Model Number(s): DAC960PG, Fab. 550107 Rev. A Year of Manufacture: 1997 Conforms to the following Product Specification(s): EMC: EN 50081-1:1992/EN 55022:1992 Class B...
Page 7 Community of Europe CE mark is rated for the DAC960PG as follows: CISPR 22 Radiated Emission EN55022, EN5082-1 Generic immunity standard for the following: IEC 801-2 ESD, IEC 801-3 Radiated, and IEC 801-4 EFT/Burst Warning! This is a Class B product. In a residential environment this product may cause radio interference, in which case the user may be required to take adequate measures.
Page 8: Introduction
DAC960PG PCI to Ultra-SCSI Raid controller. Chapter 1 is an introduction to the DAC960PG, providing an overview of what the product is, operating system platforms that are supported, and the prerequisites for product installation.
Page 9 Conventions Throughout the manual, the following conventions are used to describe user interaction with the product: The user must enter the bold text exactly as shown bold ↵ Press the Enter key Enter Press the key labeled “Enter” (or “Delete”, etc.) File, Run Select the Run option from the pull-down menu activated when the File menu pad is selected...
Page 11: Table Of Contents
Standard Package Contents ............. 1-4 Options ..................1-4 User-Supplied Items ..............1-4 Controller Functions and Features ............ 1-5 Key Features ................1-5 DAC960PG Specifications ..............1-8 Specifications (continued) ............1-9 Chapter 2 Functional Description Overview ................... 2-1 Controller Components ..............2-1 SCSI Functions .................
Page 12 Installation Overview ................. 3-1 Requirements ..................3-1 Optional Requirements ............... 3-1 Before You Begin ................3-2 DAC960PG Installation Checklist ..........3-6 Connectors and Jumpers ..............3-7 External LED Connector ............. 3-8 SCSI Termination ................3-9 Terminating Internal Disk Arrays ..........3-9 Terminating External Disk Arrays ..........
Page 13 Appendix A Enclosure Management Introduction ..................A-1 SAF-TE ....................A-1 Appendix B Intelligent Battery Backup Unit Product Description ................B-1 Features ..................B-1 IBBU Components ..............B-1 IBBU Specifications ................B-2 Electrical ..................B-2 On-board Battery ................B-2 Battery Charge Life ..............B-2 External Battery ................B-2 Module Dimensions ..............B-2 Environmental ................B-2 Functional Description ...............B-3 General Operational Description ..........B-3...
Page 14 Standby Replacement of Disks (“Hot Spare”) ........8 Stripe Order ..................9 Stripe Size .................... 9 Stripe Width ..................10 Striping ....................10 System Drives ..................10 Target ID ..................... 10 Write Back Cache ................11 Write Through Cache ................. 11 DAC960PG Installation Guide...
Page 15: Introduction
Introduction Product Description Figure 1-1. DAC960PG Three-channel RAID Controller The DAC960PG is a 1, 2, or 3-channel, high performance, PCI to Ultra- SCSI RAID controller. Some of the features which are supported by the DAC960PG controller include: • The ability to add capacity on-line while maintaining continuous access to data •...
Page 16: Saf-Te
The DAC960PG firmware resides in flash EEPROM. When the system is started, the firmware is copied into RAM and executed from there. The firmware supports RAID levels 0, 1, 0+1, 3, 5, and JBOD (Mylex RAID 7). The DAC960PG supports disk caching with up to 128 MB of Extended Data Out (EDO) RAM.
Page 17 Introduction Figure 1-2. DAC960PG Controller Component Layout 1, 2, or 3 connectors on the top edge of the DAC960PG provide the interface for internal SCSI devices. SCSI Channel 0 (and Channel 1 if installed) is also available on the end of the card for connecting to external disk array enclosures or other SCSI devices.
Page 18: Standard Package Contents
Standard Package Contents Standard Package Contents • DAC960PG PCI to Ultra-SCSI RAID controller with cache memory and Installation Guide manual Note A minimum of 4MB of memory is required for operation of the DAC960PG. • Configuration and Utilities software (DACCF 4.70 or greater) diskette and manual for controllers using firmware 4.x.
Page 19: Controller Functions And Features
1. Drives in an array can be removed and reinstalled in any order (target IDs can be switched within an array). 2. The drives’ SCSI channel assignments can be changed. 3. A DAC960PG controller can be exchanged with another DAC960 controller as long as both controllers have 4.x or higher firmware. Add Capacity Add Capacity allows the user to add one or more drives to an existing array to expand the capacity of the array.
Page 20 (up to 2 TeraBytes), as multiple large-capacity drive groups, or as individual drives (with a maximum of 32 system drives) • Up to eight DAC960PG controllers per host connect up to 180 SCSI devices • Industry-standard Fast/Wide Ultra-SCSI interface supports most...
Page 21 Introduction Enhance SCSI Performance • Fast/Wide Ultra-SCSI channels provide high-performance data transfers at up to 40 MB/second/channel • PCI bus mastering provides up to 132 MB/second burst data rates • Tag-queuing to the drives allows processing of up to 64 simultaneous multi-thread system commands or data requests •...
Page 22: Dac960Pg Specifications
I/O Processors Mylex BA-81C15, one per channel RAID (Levels supported) RAID 0, Striping RAID 1, Mirroring RAID 3, Parity RAID 5, Parity RAID 0 + 1, Striping and Mirroring (Mylex RAID 6) JBOD, Single-drive control (Mylex RAID 7) DAC960PG Installation Guide...
Page 23: Specifications (Continued)
Introduction Specifications (continued) Electrical requirements 5V ± 5% @ 3.5 Amp (Max. plus cable termination power) Environmental Temperature Operating: 0°C to +55°C (+32°F to +131°F) Storage: -20°C to +70°C (-4°F to +158°F) Humidity Operating: 10% to 90% rh (non-condensing) Non-operating 10% to 90% rh Altitude Operating:...
Page 24 DAC960PG Specifications 1-10 DAC960PG Installation Guide...
Page 25: Functional Description
Controller Components The I960 RP Processor The Intel 80960RP processor chip is the heart of the DAC960PG controller. The i960 RP is a CPU that arbitrates the primary and secondary PCI busses, the Ultra-SCSI interface, cache memory control, firmware control, and NVRAM data;...
Page 26 Controller Components Cache Memory Subsystem The DAC960PG requires a minimum of 4 MB of on-board cache memory to operate and up to 128 MB of memory can be installed. The physical memory configuration for the DAC960PG is one 72-pin SIMM.
Page 27 PCI bus and is a bridge to the secondary PCI bus. The primary and secondary PCI busses are clocked at PCI bus speed. The secondary PCI bus interfaces with up to three Mylex BA81C15 PCI to Ultra-SCSI host adapter ASICs. Each BA81C15 is dedicated to one Ultra-SCSI channel.
Page 28 • Interchange of cables The configuration information is stored in the last 128 sectors of every working physical hard disk This area is reserved by Mylex for this purpose. Management of Bad Data Firmware 4.x supports the handling of data that cannot be reconstructed at the time of a rebuild.
Page 29 Functional Description Separate Disk-stripe Size and Cache-line Size Firmware 4.x supports the configuration of disk-stripe sizing and cache-line sizing independently. This gives the user more flexibility in adjusting performance. This can be set using the DACCF utility version 4.7 or greater. System Drive Size Extensions Firmware 4.x supports system disk drive sizes of up to 2 TeraBytes.
Page 30: Scsi Functions
Multiple SCSI Format Support The standard DAC960PG provides at least one, and optionally up to three, SCSI channels for connecting disk drives or other devices, such as CD-ROM and tape drives. With the correct cabling, these devices may be any combination of Narrow or Wide, standard or FAST SCSI or Ultra-SCSI formats (see Table 2-1).
Page 31: Scsi Address (Target Id) Selection
The target ID, a SCSI address number from 0 to 15, is assigned to each device attached to a SCSI channel during installation. The default SCSI address for the DAC960PG controller is target ID 7. Subsequently, you must assign to each connected disk drive a different (unique) SCSI address, typically a target ID number from 0 through 15 (with the exception 7, which is reserved on each channel for the controller).
Page 32: Drive Organization
Physical Drives (Drive Groups or Packs) Using the DAC960PG up to eight individual disk drives can be used together to form a pack or drive group of physical drives that will be used to comprise the array’s logical unit capacity.
Page 33: Configuration On Disk
Mylex Format The necessary configuration information is stored in NVRAM on the controller as well as on the last 128 sectors on every hard disk that is currently part of the controller’s configuration.
Page 34 If there is a mismatch, it means the device just read is an unidentified device. If a configuration header is not in the Mylex format, the corresponding drive is assumed to be new. Such a drive is also unidentified. If all drives...
Page 35 Functional Description Figure 2-4. Configuration on Disk Flowchart Manual No. 771971 2-11...
Page 36: Raid Management
RAID technology, and two special versions that are specific only to the DAC960 family of RAID controllers. Each version (referred to as a RAID Level) that is supported by the DAC960PG is shown in Table 2-2. An appropriate RAID level is selected when the logical drives are defined or created using a configuration software utility such as DACCF.
Page 37: Raid Techniques And Terms
RAID Techniques and Terms The techniques of disk striping, mirroring, and parity (redundancy) are fundamental elements of RAID technology performed by the DAC960PG. More detailed information on how to apply these techniques can be found in the DACCF Utilities Installation Guide and User Manual. or the GAM manual.
Page 38 This method can significantly increase disk system throughput, particularly for transferring large, sequential data blocks. Figure 2-7. Block Striping Figure 2-8. Drive Group Mapped for Block Striping 2-14 DAC960PG Installation Guide...
Page 39 Functional Description Striping with Parity (RAID 3 and RAID 5) Striping with parity (rotated XOR redundancy) is a method of providing complete data redundancy that requires only a fraction of the storage capacity than mirroring for storing redundant information. In a system configured under RAID 3 or RAID 5 (which requires at least three SCSI drives), all data and parity blocks are divided between the drives in such a way that if any single drive is removed (or fails), the data on the missing drive can be regenerated using the data on the remaining drives...
Page 40 RAID Management Figure 2-10. Block Striping with Parity (RAID 5 standard) 2-16 DAC960PG Installation Guide...
Page 41: Striping Terminology
Functional Description Striping with Mirroring (RAID 0+1) RAID 0+1 (Mylex RAID 6) is a combination of RAID 0 (striping) and RAID 1 (mirroring). The advantages of RAID 0+1 are fully mirrored data and better performance than RAID 1. The disadvantage of RAID 0+1 is its 50% utilization capacity (if all drives are the same size).
Page 42: Drive Management
Drive Management Drive Management The DAC960PG functions that monitor and control the operation of the physical drives and logical units are instrumental to the controller’s ability to perform RAID management and automated error recovery tasks. Controlling Physical Drive States The state of a physical drive refers to a SCSI drive's current operational status.
Page 43: Controlling Logical Unit States
RDY to SBY (standby) when the configuration is saved to memory. Controlling Logical Unit States The state of a logical unit on a DAC960PG can be ON-LINE, CRITICAL, or OFF-LINE. Notice that the same term on-line is used for both physical drives and logical units.
Page 44: Controlling Standby Replacement Drives (Hot Spares)
Controlling Standby Replacement Drives (Hot Spares) The standby replacement drive, or hot spare, is one of the most important features the DAC960PG provides to achieve automatic, non-stop service with a high degree of fault-tolerance. With the standby rebuild function, the...
Page 45: Hot-Swap Drive Replacement
To use the automatic standby rebuild feature, it is necessary to always maintain a standby disk in the system. A standby disk can be created when the DAC960PG configuration is created or changed using the DACCF software utility, all disks attached to the controller that are On-line and not assigned to a drive group will be automatically labeled as standby disks.
Page 46: Checking Disk Consistency
To verify RAID 3 or RAID 5 redundancy, a consistency check reads all associated data blocks, computes parity, reads parity, and verifies that the computed parity matches the read parity. 2-22 DAC960PG Installation Guide...
Page 47: Cache Management
Functional Description Cache Management The DAC960PG provides performance enhancement of data transfers through its on-board cache memory. The controller supports cache memory sizes from 4 MB (minimum) to 128 MB (maximum). Cache memory is allocated by the controller memory management functions for Read Cache and Write Cache.
Page 48 Cache Management 2-24 DAC960PG Installation Guide...
Page 49: Installation Overview
• SCSI termination device(s) as required Refer to the Configuration & Utilities diskette file DISKLIST.TXT for a list of disk drives and other devices that are compatible with the DAC960PG. Optional Requirements The following optional items also may be required, depending on your application or the type of installation: •...
Page 50: Before You Begin
Before You Begin . . . Before You Begin . . . Installing the DAC960PG PCI to Ultra-SCSI RAID controller is no more difficult than installing any PCI adapter card. Just follow these common- sense rules and the installation procedures should go flawlessly:...
Page 51 Installation Notes: DAC960PG PCI to Ultra-SCSI RAID Controller Setup: There are no jumper settings on the DAC960PG to be configured by the user. Controller termination is automatic as long as the end of the SCSI bus away from the controller is properly terminated. If there are devices...
Page 52 ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ Reserved for DAC960PG ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______...
Page 53 ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ Reserved for DAC960PG ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______ ___________________ ________ ______...
Page 54: Dac960Pg Installation Checklist
Prepare the host system according to its documentation. ____ 3. Determine the SCSI ID and termination requirements. ____ 4. Check the DAC960PG jumper settings (only pins 1 & 2 on JP12 should have a jumper). ____ 5. Mount the controller into the system; connect the cables and terminators.
Page 55: Connectors And Jumpers
Installation Connectors and Jumpers Figure 3-1. DAC960PG Component Locations Table 3-1. Jumper Blocks and Connectors Component Description Default Setting Connector for harness to front panel LEDs (optional) Not used JP10 Select manufacturing diagnostics - Do Not Install Jumper Off JP12 Jumper pins 1&2 for +5V RP - Leave at Default...
Page 56: External Led Connector
One or more of the SCSI channels on the controller is transmitting or receiving data. JP4, Pin 6 Cache Dirty The cache memory on the DAC960PG (Write Pending) contains data that is more current than the data on the hard drive(s).
Page 57: Scsi Termination
SCSI bus without having to add or remove termination. The DAC960PG controller has on board ALT-2 type SCSI terminators on all drive channels. The on board termination logic will detect the presence of a...
Page 58 SCSI Termination Figure 3-3. Internal Disk Array, Single-ended SCSI Termination 3-10 DAC960PG Installation Guide...
Page 59: Terminating External Disk Arrays
If the all the SCSI devices on a channel are connected to the external connector of a channel, the end of the SCSI bus farthest from the controller must have a terminator installed. The DAC960PG will automatically enable on board termination at its end of the SCSI bus. Caution...
Page 60: Terminating Combined Internal And External Disk Arrays
SCSI devices are connected to the external connector of the same channel, the two ends of the SCSI bus farthest from the controller must each be terminated. The DAC960PG will automatically disable its on board SCSI termination. Figure 3-5. Combination External/Internal Disk Array, SCSI Termination Selecting the Correct Terminator Use ALT-2 type external SCSI terminators for operating a SCSI channel at 10M Bytes/second (or faster) synchronous transfer rates.
Page 61: Configuring The Scsi Devices
See the specifications accompanying the SCSI drive for proper jumper settings. Also, the DAC960PG should be configured to spin-up the drives at regular intervals by giving each drive a spin-up command. See the DACCF Utilities Installation Guide and User Manual for more information on the disk drive spin-up options.
Page 62: Scsi Cabling
Note The SCSI transfer rate can be individually selected for each of the three channels on the DAC960PG. For more information, refer to the DACCF Utilities Installation Guide and User Manual.
Page 63: Cable Lengths
Installation Cable Lengths Generally speaking, as SCSI data transfer rates increase, maximum allowable cable lengths decrease. Transfer rates of 5 MB/sec for 8-bit SCSI or 10 MB/sec for 16-bit SCSI will normally allow a 6 meter (20 foot) maximum cable length on a channel. Transfer rates of 40 MB/sec for 16-bit Ultra SCSI permit a maximum cable length of only 1.5 meters, if more than 4 devices are on the channel.
Page 64: Connecting Non-Disk Devices
SCSI ID, regardless of the channel of the DAC960PG to which they are connected. For instance, the general rule for UNIX systems is to set the tape to SCSI ID 2, the CD-ROM to SCSI ID 5, with both devices connected to channel 0.
Page 65: Using A Ups
Installation You can work around this problem by connecting the non-disk devices to one channel of the DAC960PG, while connecting the hard drives to the other channels. However, most people do not wish to give up one channel of a high-performance, caching disk array controller for this purpose.
Page 66: Cache Battery Backup Option
Data maintained in the cache will be written to disk after power is restored. The optional cache battery backup module is available for the DAC960PG to provide, in the event of a power failure, battery backup to the SIMM module installed on the controller.
Page 67: Start-Up Sequences
BIOS options to be considered: BIOS enable/disable, CD-ROM boot enable/disable, and a 2 or 8 Gigabyte Disk Drive Geometry setting. The DAC960PG BIOS provides a single threaded interface to access up to eight logical units (system drives) on each controller.
Page 68: Setting Bios Options
Setting BIOS Options There are three DAC960PG BIOS options that need to be considered and possibly changed during installation of the DAC960PG. This is usually a one-time requirement. The BIOS options are: •...
Page 69 If the BIOS is disabled, it will not be possible to change the other options. If the boot drive is on a DAC960PG, then drive geometry changes should not be attempted unless the boot drive is going to be reformatted. The option to...
Page 70 Setting BIOS Options Figure 4-2. BIOS Options Menu when Drive Geometry Option is Selected Press the Esc key to exit the BIOS options menu. The following message will be displayed: DAC960PG Installation Guide...
Page 71: Bios Enable Or Disable
The default for this option is for the BIOS to be enabled. Disabling the BIOS prevents the DAC960PG from being the boot controller. While the BIOS is disabled, it will not be possible to make changes to the other BIOS options.
Page 72: Enable 8 Gbyte Or 2 Gbyte Drives
The drive geometry must be set and then the drive must be formatted (or reformatted). The DAC960PG ships with the default BIOS geometry set to 2 GB. This means that the BIOS will only be able to see the firsst 2 gigabytes of any drive that has been configured on the DAC960PG.
Page 73: Drive Check Error Messages
Start-up Sequences Drive Check Error Messages If the firmware finds a valid DAC960PG configuration, but it doesn't match the SCSI drives currently installed, one or more of the following messages will be displayed: Unidentified device found at channel x..Device identified for chn x, tgt y found at chn x', tgt y'...
Page 74 No system drives found: None installed X system drives installed The BIOS repeats the same process for additional DAC960PG controllers present in the system. Then it proceeds to boot, if possible, from the first system drive on the first DAC960PG controller.
Page 75: Aborted Installation
DAC960PG. The ‘Write Pending’ indicator is especially important when preparing to power-down the system. The DAC960PG is a caching controller with up to 128MB of cache memory, data may still be in the cache, waiting to be written to the disk drives, when the system reports that a write command was completed.
Page 76 System Reboot or Power Down 4-10 DAC960PG Installation Guide...
Page 77: Enclosure Management
Appendix A Enclosure Management Introduction The DAC960PG supports enclosure management protocols. This feature allows the host to monitor drive enclosures and detect certain faults or operating environment conditions. The host can make a decision to shut down the system or issue a warning based on the type of fault detected.
Page 78 SAF-TE DAC960PG Installation Guide...
Page 79: Intelligent Battery Backup Unit
The battery backup module monitors the write back cache on the DAC960PG, and provides power to the cache if it contains data not yet written to the drives when power is lost.
Page 80: Ibbu Specifications
Module Dimensions Length: 3.75 inches Width: 2.875 inches Environmental Temperature Operating: 0ºC to +40ºC (+32ºF to 104ºF) Storage: -40ºC to +60ºC (-40ºF to +140ºF) Humidity Operating: 45% to 85% relative humidity Non-operating: 45% to 85% relative humidity DAC960PG Installation Guide...
Page 81: Functional Description
Intelligent Battery Backup Unit Functional Description General Operational Description The IBBU consists of the following five blocks 1. Electronic switches that connect between V and the DC-DC converter output to V (actual voltage being applied). 2. Power fail (PF) detector that detects the presence or absence of V 3.
Page 82: Battery And Charge Circuit
The battery power meter indicates the battery capacity in hours. It will indicate a charge duration of up to 100 hours. The firmware will detect the Mylex supplied SIMM and assign a value based upon the charge level of the battery and the power consumption rate of the SIMM.
Page 83: Installation
The only tool needed for the installation is a small, flat-blade screwdriver Procedure 1. If the DAC960PG is not already removed from the system, power the system down and then remove the DAC960PG. 2. Remove the loopback plug from J5 on the DAC960PG. Keep the loopback plug in a safe place, in case the IBBU needs to be removed at a later time.
Page 84 DAC960PG if the connectors are plugged in correctly. 6. Be sure the 4 standoffs line up with the 4 holes in the DAC960PG. Place a nylon screw through a hole from the back of the DAC960PG into a standoff, and turn the screw to the right until it is snug (not too tight).
Page 85: Operation
Intelligent Battery Backup Unit Operation Battery Conditioning Prior to Use Battery conditioning is automatic. There are no manual procedures for battery conditioning or preconditioning to be performed by the user. Set-up – Enabling the Write-Back Cache The write-back cache is enabled by toggling the write-back/write-through mode switch.
Page 86: Battery Backup Capacity
The IBBU’s backup capacity varies with the memory configuration installed on the DAC960PG. Battery backup capacity can be reasonably expected according to Tabe 4-1 Table 4-1. IBBU Capacity vs. Cache Memory Configuration...
Page 87: Removing The Battery Backup Module
1. The NiCd battery will no longer accept a charge properly (NiCd battery life expectancy is approximately 5 years). 2. The cache memory needs to be removed from the DAC960PG for replacement or upgrade. WARNING Do not attempt to install, remove, or change a cache SIMM on the DAC960PG with the IBBU installed.
Page 88: Recycling The Battery
Battery Backup Capacity Caution If you plan to operate your DAC960PG without the IBBU, be sure to reinstall the loopback plug (see the “Mechanical Installation Procedure” section and Figure B-2). Recycling the Battery The on-board battery that comes with the IBBU has the logo of the Rechargeable Battery Recycling Corporation (RBRC) stamped on it.
Page 89 Intelligent Battery Backup Unit Information on the RBRC program and the locations of participating recycling centers can be obtained by telephoning 1–800–8–BATTERY (in the USA), and following the recorded instructions. The information obtained from this telephone number is updated frequently, since the RBRC program is growing, and new recycling locations are being added regularly.
Page 90 Battery Backup Capacity B-12 DAC960PG Installation Guide...
Page 91: Glossary
Cache Line Size See “Segment Size.” Channel Refers to one SCSI bus on a DAC960 Series controller. Each DAC960PG provides at least one channel, or additional channels with optional upgrades. Consistency Check Refers to a process where the integrity of redundant data is verified. For example, a consistency check of a mirrored drive will make sure that the data on both drives of the mirrored pair is exactly the same.
Page 92: Disk Failure Detection
If the command times out again, the disk could be “killed” (taken “offline”) by the controller (its state changed to “dead”). DAC960PG controllers also monitor SCSI bus parity errors and other potential problems. Any disk with too many errors will also be ‘killed’.
Page 93: Hot Replacement Of Disks ("Hot Swap")
The battery backup module monitors the write back cache on the DAC960PG, and provides power to the cache if it contains data not yet written to the drives when power is lost.
Page 94: Logical Drives
Refers to the 100% duplication of data on one disk drive to another disk drive. Each disk will be the mirror image of the other. Pack See “Drive Groups (or Drive Packs).” Parity See “Rotated XOR Redundancy.” Glossary-4 DAC960PG Installation Guide...
Page 95: Raid
Glossary RAID RAID stands for Redundant Array of Independent Disks. The DAC960PG controllers implement this technology to connect up to 15 SCSI devices per channel. Several different forms of RAID implementation have been defined. Each form is usually referred to as a “RAID level.” All the RAID levels supported by DAC960 Series controllers are shown below.
Page 96: Replacement Table
DEAD in one session, it will stay in the DEAD state until a change is made either by using a system level utility or after a rebuild. Each of the states is described below: Glossary-6 DAC960PG Installation Guide...
Page 97: Segment Size
“chunk” that will be read or written at one time. Under DACCF, the segment size (also known as “cache line size”) should be based on the stripe size you selected. The default segment size for Mylex DAC960PG controllers is 8K. Manual No. 771971 Glossary-7...
Page 98: Session
4. A disk may also be added (attached at a later time) to a running system and labeled as standby by using the “DAC960 Software Kit” (see appropriate chapters for DAC960 utilities for a particular operating system). Glossary-8 DAC960PG Installation Guide...
Page 99: Stripe Order
Glossary During the automatic rebuild process, system activity continues as normal. System performance may degrade slightly during the rebuild process. To use the standby rebuild feature, you should always maintain a standby SCSI disk in your system. When a disk fails, the standby disk will automatically replace the failed drive and the data will be rebuilt.
Page 100: Stripe Width
DAC960 Series controller. Target ID A target ID is the SCSI ID of a device attached to a DAC960PG controller. Each SCSI channel can have up to 15 attached SCSI devices (target ID from 0 to 6, and 8 to 15).
Page 101: Write Back Cache
Glossary Write Back Cache Refers to a caching strategy whereby write operations result in a completion signal being sent to the host operating system as soon as the cache (not the disk drive) receives the data to be written. The target SCSI drive will receive the data at a more appropriate time, in order to increase controller performance.
Page 102 Glossary Glossary-12 DAC960PG Installation Guide...
Page 103 Battery Recycling B-10 Start-up 4-6 BIOS Enable or Disable 4-5 BIOS Options 4-2 BIOS Start-up Sequence 4-1 Firmware 2-2 Functional Description DAC960PG 2-1 Cable Lengths 3-15 IBBU B-3 Cabling Functions and Features 1-5 SCSI 3-14 Cabling and Termination 2-6 Cache Battery Backup 3-18...
Page 104 DAC960PG 1-1 UPS 3-17 IBBU B-1 RAID Management 2-12 RAID Techniques and Terms 2-13 JBOD 2-13 Mirroring (RAID 1) 2-13 Striping (RAID 0) 2-14 Striping with Parity (RAID 3 and RAID 5) 2-15 Recycling the Battery B-10 Index-2 DAC960PG Installation Guide...

Mylex DAC960PG Installation Manual

Chapter 1 Introduction

Chapter 2 Functional Description

Chapter 3 Installation

Chapter 4 Start-Up Sequences

Appendix A Enclosure Management

Appendix B Intelligent Battery Backup Unit

Glossary

Quick Links

Installation Guide

Related Manuals for Mylex DAC960PG

Summary of Contents for Mylex DAC960PG

Table of Contents