Quantum 10K II - Manual (Page 296)

SCSI Description
Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives 5–229
5.53 XDREAD (10) Command (52h)
The XDREAD (10) command requests that the target transfer to the initiator the
XOR data generated by an XDWRITE (10) command. The XOR data transferred is
identified by Logical Block Address and transfer length that are the same as those
specified in a prior XDWRITE (10) command. If a match is not found, the command
is terminated with a CHECK CONDITION status. The sense data is set to
ILLEGAL REQUEST: INVALID FIELD IN CDB.
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (52h)
1 Reserved
2 - 5 Logical Block Address
6 Reserved
7 - 8 Transfer Length
9 Control
Figure 5–113 XDREAD (10) Command Descriptor Block — Data Format
Table 5–107 XDREAD (10) Command — Field Descriptions
Field Description
Logical Block Address Specifies the address of the prior XDWRITE (10)
command that generated the XOR data in the buffer
that is being requested.
Transfer Length Specifies the number of contiguous logical blocks of
data to transfer. This length must match the length of
the original XDWRITE (10) command that generated
the XOR data requested.