HP C2246 Technical Reference Manual page 63

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Format Unit
Format Unit
The FORMAT UNIT command formats the Target media into Initiator-addressable logical
blocks according to Initiator defined options. During execution of the FORMAT UNIT
command, the Target may perform a media defect management algorithm (which can be
controlled by the Initiator using optional forms of the command). Defect management
instructions (if any) are contained in the Defect List supplied to the Target in the Data Out
phase of the command.
The FORMAT UNIT command ensures that the media is formatted so that all data blocks
can be accessed. Any data residing on the media before this command is issued will be
lost. Any log information will be cleared by the format operation. The current Mode Select
opera.ting parameters will become the saved values if the DSP bit in the defect list header is
zero (0).
There are four possible sources of defect location information during execution of the
FORMAT UNIT command:
Plist (Primary Defect List). The list of permanent defects supplied by the original
manufacturer. The Plist is stored outside of the Initiator-accessible logical block space. The
Plist is accessible by the Target (to reference while formatting), but is not normally accessible
by the Initiator except through the READ DEFECT command. Once created, the original
Plist is not subject to change. The Format Unit command does not affect the Plist.
Clist (Target Certification List). This list includes defects detected by the Target during an
optional certification process executed during the FORMAT UNIT command. This list will be
added to the Glist.
Dlist (Data Defect List). Supplied by the Initiator in the Data Out phase of the FORMAT
UNIT command.
Glist (Grown Defect List.) Maintained by the Target and includes all defects sent to the
Target from the Initiator (the Dlist ), any defects identified by the Target during previous and
current FORMAT UNIT operations, and any defects identified by a REASSIGN BLOCKS
command. The Glist does NOT include the Plist.
Format Unit Command Descriptor Block (COB)
Bit
Byte
7
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6
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5
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4
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3
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2
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1
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00
Opcode= 04H
01
Logical Unit Number
I
FMTDTA
I
CMPLST
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Defect List Format
02
Vendor Unique
03-04
{MSB=03} Interleave (LSB=04)
05
Control Byte
FMTDTA (Format Data). Indicates whether the Initiator will send additional defect
information (Dlist) to the Target. If set to zero (0),
there will be no Data Out phase,
the Target will not receive a new Dlist,
all previous defect information ( Glist) is retained,
and the CMPLST bit and the Defect List Format field will have no effect.
0
SCSI Command Descriptions A-7