Read (10) - (28) - Hitachi HUS151473VL3800 - Ultrastar 73.4 GB Hard Drive Specifications

17.16 READ (10) - (28)

Table 109: READ (10) - (28)
Byte
7
0
1 Reserved = 0
(MSB)
2-5
6
(MSB)
7-8
9 VU = 0
The READ (10) command requests the drive to transfer data to the Initiator. The larger LBA and Transfer Length fields permit
greater quantities of data to be requested per command than with the READ command and are required to access the full LBA
range of the larger capacity drives.
• Transfer length The number of contiguous blocks to be transferred. If the transfer length is zero, the seek occurs, but
no data is transferred. This condition is not considered an error. If read ahead is enabled, a read ahead is started after
the seek completes.
• 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.
• FUA (Force Unit Access) bit of one indicates that the data is read from the media and not from the cache. A FUA bit
of zero allows the data to be read from either the media or the cache.
• RelAdr (Relative Block Address) is not supported. Must be set to zero. Relative addressing is not supported. If
RelAdr is set to 1, Check Condition status is returned with a sense key of Illegal Request and additional sense code
of Invalid Field in CDB.
If the transfer length is zero, no data is transferred. The CDB is validated and protocol checked and, if no problems are found,
Good status is returned immediately. This condition is not considered an error.
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6 5 4
Command Code = 28h
DPO
Logical Block Address
Reserved = 0
Transfer Length
Reserved = 0
Hitachi Ultrastar 15K147 SCSI Hard Disk Drive Specification
Bit
3 2
FUA Reserved = 0
157
1 0
RelAdr
= 0
(LSB)
(LSB)
FLAG LINK