Quantum 10K II - Manual (Page 300)

SCSI Description
Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives 5–233
5.55 XPWRITE (10) COMMAND (51h)
The XPWRITE (10) command requests that the target XOR the data transferred
with the data on the medium then writes the XOR data to the medium.
The Logical Block Address field specifies the Starting Logical Block address for the
target to read data from its medium. It also specifies the starting Logical Block
Address at which to write the XOR result to its medium.
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (51h)
1 Reserved DPO FUA Reserved
2 - 5 Logical Block Address
6 Reserved
7 - 8 Transfer Length
9 Control
Figure 5–115 XPWRITE (10) Command Descriptor Block — Data Format
Table 5–109 XPWRITE (10) Command — Field Descriptions
Field Description
DPO Disable Page Out. When the value = 0, the drive
caches the data read, using its normal Logical Read
Unit Policies.
When the value = 1, the drive assigns to logical blocks
accessed the lowest priority for being fetched into or
retained by the cache.
FUA Force Unit Access. When the value is 0, the drive is
allowed to satisfy the read with cache-resident data.
A value of 1 indicates that the drive accesses the
media in performing the command.
(continued)