Section 5
SCSI
Programming Guidelines
5.11.22
READ DEFECT DATA COMMAND: OPCODE = 37(hex)
The READ DEFECT DATA command (Table 5-38) requests that the target transfer the medium defect data
to the initiator.
TABLE
5-38
READ
DEFECT
DATA Command
Bit
7
6
5
4
3
2
1
o
Byte
0
OPCODE=37H
I
LUN=O
RESERVED
=0
2
RESERVED=O
P
I
G
t
DEFECT LIST FORMAT
3-6
RESERVED
=0
7-8
(MSB)
ALLOCATION
LENGTH
(LSB)
9
vu=o
1
RESERVED
=0
I
F
I
L
P • PRIMARY (BYTE 2, BIT 4) - Set to one indicates that the initiator requests the primary
(factory) list
of
defects be returned.
G·
GROWN (BYTE 2, BIT 3) - Set to one indicates that the initiator requests the grown list
of
defects be returned.
NOTE: With bits P and G both set
toa
value
of
one, the ProDrive is requested to return the
primary and the grown list
of
defects. Only the Defect List Header bytes will be returned
if
both the P and G bits are set to a value
of
zero.
DEFECT LIST FORMAT (Byte 2, Bits
2·1)
- Specifies the preferred format for the defect
list to be returned by the
ProDrive.
If
a format not supported by the ProDrive is requested, the
drive will return the defect data in
Physical Sector Format. In this case, the ProDrive will create the
CHECK
CONDITION status with RECOVERED ERROR sense key after the defect list data list has
been transferred. Two defect data formats are supported by the
ProDrive:
PHYSICAL SECTOR FROM INDEX FORMAT (IOIB) - This format will return the physical
cylinder. head and sector location from index
of
the medium defects.
BYTES OFFSET FROM INDEX
(1
<>Os)
-This format will return the physical cylinder, head and
the bytes offset from index
of
the defect location. The offset number reported represents the first
byte
of
the defective sector.
ALLOCATION LENGTH (Bytes 7-8)- Specifies the number
of
bytes the initiator has allocated
for returned defect data.
An allocation length
of
zero indicates that no defect data are to be transferred.
Any other value indicates the maximum number
of
bytes to be transferred. The ProDrive will
terminate the DATA
iN
phase when allocation length bytes have been transferred or when all available
defect data have been transferred to the initiator, whichever is less.
The defect data list contains a four byte header (Table 5-39) followed by zero or
more defect descriptors.
5-64
SCSI Programming Guidelines
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