Section 5
SCSI Programming Guidelines
5.11.5
REASSIGN BLOCKS COMMAND: OPCODE = 07(hex}
The REASSIGN BLOCKS command (Table 5-16) requests the
ProDrive
to reassign the defective logical
blocks to areas
on
the drive reserved for this purpose.
The initiator transfers a defect list during the DATA
OUT
phase following the command bytes; the defect
list contains the logical block addresses to be reassigned by the
ProDrive.
The drive will reassign the
physical medium used for each logical block address in the list. The data contained in the logical blocks
specified in
the
defect list will be preserved
if
recoverable within the limits prescribed by MODE SELECT
error recovery parameters; the data in all other logical blocks on the medium will be preserved.
If
a logical
block that has previously been reassigned is
specified to
be
reassigned, the block will be reassigned again.
The defective block address will
be added to the drive's field replacement defect map.
NOTES: The REASSIGN BLOCKS command should not
be
used to redundantly reassign defective
logical blocks which have already been so reassigned with the automatic reallocation feature
of
MODE
SELECT.
Byte
0
1
2-4
5
Block reassignment can degrade performance by requiring spare locations to
be
accessed. This
can
be
remedied by moving a file to a more appropriate area (as determined using the READ
CAPACITY command) or possibly by reassigning all logical block addresses with the
FORMAT UNIT command.
TABLE
5-16
REASSIGN
BLOCKS
Command
Bit
7
6
5 4
3 2 I
o
OPCODE=07H
LUN=O
1
RESERVED
=0
RESERVED
=0
VU=O
I
RESERVED=O
I
F
I
L
The REASSIGN BLOCKS defect list (Table 5-17) contains a four-byte
header
followed by one
or
more
defect descriptors. The length
of
each defect descriptor is four bytes. The defect list length field specifies
the total length in bytes
of
the defect descriptors that follow. The defect list length is, therefore, equal to
four times the number
of
defect descriptors.
SCSI
Programming
Guidelines
5-35
To Next Page
Loading...