User Manual

SCSI Commands Reference Manual, Rev. J 162
www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)
3.25 READ DEFECT DATA (12) command
3.25.1 READ DEFECT DATA (12) command overview
The READ DEFECT DATA (12) command (see table 128) requests that the device server transfer the medium defect data to the
data-in buffer.
See the READ DEFECT DATA (10) command (see 3.24) for the definitions of the fields in this command that are not described in this clause.
ADDRESS DESCRIPTOR INDEX field
The ADDRESS DESCRIPTOR INDEX field specifies the index of the first address descriptor (see 3.3.5.1) in the defect list that the device server
shall return. If the ADDRESS DESCRIPTOR INDEX field is set to:
a) a value less than the number of available address descriptors, then the device server shall transfer a defect list beginning with the
address descriptor that is at the ADDRESS DESCRIPTOR INDEX field value multiplied by the size of the address descriptor; or
b) a value greater than or equal to the number of available address descriptors, then the device server shall return a zero
length defect list.
ALLOCATION LENGTH field
The ALLOCATION LENGTH field is defined in SPC-5. The application client is responsible for comparing the allocation length requested in the
CDB with the DEFECT LIST LENGTH field value returned in the parameter data to determine whether a partial list was received. If the length of
all the address descriptors that are available is greater than FFFF_FFFFh, then the device server shall transfer the length of address descriptors
specified by the allocation length or the DEFECT LIST LENGTH field value plus eight, whichever is less, and complete the command with GOOD
status.
Table 128 READ DEFECT DATA (12) command
Bit
Byte
7 6 5 4 3 2 1 0
0 OPERATION CODE (B7h)
1 Reserved REQ_PLIST REQ_GLIST DEFECT LIST FORMAT
2
ADDRESS DESCRIPTOR INDEX. . .
5
6 (MSB)
ALLOCATION LENGTH. . .
9 (LSB)
10 Reserved
11 CONTROL