Hitachi ULTRASTAR 15K450 HUS154530VLF400 - Manual (Page 289)

Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
273
19.46 VERIFY (2F)
Table 234: VERIFY (2F)
The VERIFY command requests that the drive verify the data written on the media. A verification length of zero indicates that
no data will be transferred. This condition is not considered an error.
• ByteChk bit set to zero indicates that the data is read from the disk and verified using ECC.If an ECC error is
detected in the verify process, Check Condition status is returned with sense key set to Medium Error. ByteChk bit
set to one indicates that byte-by-byte comparison is performed between the data on the disk and data transferred from
the initiator during the data-out phase.
If the comparison is unsuccessful, the command is terminated with Check Condition status and the sense key is set
to Miscompare.
• DPO (Disable Page Out) bit of one indicates that the data accessed by this command is to be assigned the lowest pri-
ority for being written into or retained by the cache. A DPO bit of one overrides any retention priority specified in the
Mode Select Page 8 Caching Parameters. A DPO bit of zero indicates the priority is determined by the retention pri-
ority. The Initiator should set the DPO bit when the blocks read by this command are not likely to be read again in the
near future.
If caching is enabled, the command performs an implied FUA and an implied Synchronize Cache before starting the VERIFY.
This ensures that the medium, not the cache, is being verified.
The command stops on Check Condition and reports the LBA in error. The command must be reissued, starting with the next
LBA, to verify the remainder of the Drive.
The Verification Length is the number of blocks to check.
The data (if any) from the data-out phase and the data from the media are not retained in the cache. Therefore, the DPO bit has
no effect on this command and is ignored.
VRPROTECT defines the manner in which protection information read from disk shall be checked during processing of the
command. Protection information is stored on disk, and may be validated using the drive's internal checking algorithms, and
also byte-by-byte compared using data from the initiator when ByteChk=1.
Byte
BIT
7 6 5 4 3 2 1 0
0 Command Code = 2Fh
1 VRPROTECT DPO Reserved = 0
Byte
Chk
RSVD
= 0
2-5
(MSB)
Logical Block Address
(LSB)
6 Reserved = 0
7-8
(MSB) Verification Length
(LSB)
9 VU = 0 Reserved = 0 FLAG LINK