HGST Ultrastar 7K4000 (SAS) Hard Disk Drive Specification
261
18.56 WRITE AND VERIFY (10) - (2E)
Table 219: WRITE AND VERIFY (10) - (2E)
WRITE AND VERIFY command requests that the drive writes the data transferred from the Initiator to the medium and then
verify that the data is correctly written. If caching is enabled, an implied FUA (Force Unit Access) and an implied Synchronize
Cache are performed before starting the operation. This insures that data from the disk, not the cache, is verified.
• See the WRITE (10) command description for the definition of the WRPROTECT field.
• Transfer Length is the number of contiguous blocks to transferred. If the transfer length is zero, the seek occurs, but
no data is transferred. This condition is not considered an error.
If caching is enabled, the command performs an implied FUA and an implied Synchronize Cache before starting the
operation. This insures that the medium, not the cache, is being verified.
• ByteChk bit set to zero indicates that the data is read back from the disk and verified using LDPC after the successful
write operation. If an LDPC 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 data on
the disk starting the block specified in LBA field and data transferred from the Initiator.
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 written by this command is to be assigned the lowest prior-
ity 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 written by this command are not likely to be read again in the
near future.
Byte
Bit
76543210
0 Command Code = 2Eh
1 WRPROTECT DPO Reserved = 0
Byte
Chk
Obso-
lete
2-5
(MSB)
Logical Block Address
(LSB)
6 Reserved = 0
7-8
(MSB) Transfer Length
(LSB)
9 VU = 0 Reserved = 0 FLAG LINK
To Next Page
Loading...
Need help?
General
