User Manual

SCSI Commands Reference Manual, Rev. J 235
www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)
BYTCHK field
If the byte check (BYTCHK) field is set to 00b, then:
a) no Data-Out Buffer transfer shall occur;
b) for any mapped LBA specified by the command, the device server shall check the protection information from the verify
operation based on the VRPROTECT field as defined in table 208; and
c) for any unmapped LBA specified by the command, the verify operation shall complete without error.
If:
a) the BYTCHK field is set to 01b or 11b;
b) the VBULS bit is set to zero in the Block Device Characteristics VPD page (see 5.4.3); and
c) any LBA specified by the command is unmapped (i.e., deallocated or anchored),
then the device server shall terminate the command with CHECK CONDITION status with the sense key set to MISCOMPARE and
the additional sense code set to MISCOMPARE VERIFY OF UNMAPPED LBA.
If:
a) the BYTCHK field is set to 01b or 11b; and
b) either:
A) the VBULS bit is set to one in the Block Device Characteristics VPD page; or
B) all LBAs specified by the command are mapped,
then:
a) if the BYTCHK field is set to 01b, then the Data-Out Buffer transfer shall include the number of logical blocks specified by
the VERIFICATION LENGTH field;
b) if the BYTCHK field is set to 11b, then:
A) the Data-Out Buffer transfer shall include one logical block; and
B) the device server shall:
1) duplicate the single logical block, as described in the WRITE SAME command (see 3.73), the number of times
required to satisfy the VERIFICATION LENGTH field; and
2) place the duplicated data in the Data-Out Buffer;
c) the device server shall check the protection information transferred from the Data-Out Buffer based on the VRPROTECT
field as defined in table 210;
d) for any mapped LBA specified by the command, the device server shall perform the verify operation and check the protec-
tion information from the verify operation based on the VRPROTECT field as defined in table 209;
and
e) the device server shall perform:
A) a compare operation of:
a) user data from the verify operations; and
b) user data from the Data-Out Buffer;
and
B) a compare operation based on the VRPROTECT field as defined in table 211 of:
a) protection information from the verify operations; and
b) protection information from the Data-Out Buffer.
The order of the user data and protection information checks and comparisons is vendor-specific.
If a byte-by-byte comparison is unsuccessful for any reason, the device server shall terminate the command with CHECK
CONDITION status with the sense key set to MISCOMPARE and the additional sense code set to the appropriate value for the
condition.