Xpwrite Command (51H) - Seagate Ultra160 Product Manual

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8.64

XPWRITE command (51h)

The XPWRITE command (see Table 254) requests that the target Xor the data transferred to it with the data on
the medium and then writes the Xor data to the medium. For additional information about Xor commands, see
Section 8.61.1.
Table 254: XPWRITE command (51h)
Bit 7
Byte
0 OPERATION CODE (51h)
1
2 (MSB)
3
4
5
6 Reserved
7 (MSB)
8
9 CONTROL [5]
[1] If the Disable Page Out (DPO) bit is set to one, no data is cached. The DPO bit is only meaningful if the
RCD bit of MODE SELECT Page 8 is set false (caching enabled).
[2] A Force Unit Access (FUA) bit of one indicates that the Write command shall not return Good status until
the logical blocks have actually been written on the media. The FUA bit is only meaningful if the WCE bit
of MODE SENSE page 8 is true.
[3] The LOGICAL BLOCK ADDRESS field specifies the starting LOGICAL BLOCK ADDRESS at which the
target shall read data from its medium. It also specifies the starting LOGICAL BLOCK ADDRESS at which
the Xor result data is to be written to the medium.
[4] The TRANSFER LENGTH field specifies the number of blocks to be read from the XPWRITE target
medium for the Xor operation. It also specifies the number of blocks to be written to the medium after the
Xor operation.
[5] See Table 61, "CONTROL field," in Section 7.2.1.
6 5
Reserved
LOGICAL BLOCK ADDRESS [3]
SCSI Interface Product Manual, Rev. B
4 3
DPO [1] FUA [2]
TRANSFER LENGTH [4]
2 1
Reserved
(LSB)
(LSB)
0