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Fibre Channel Interface Manual, Rev. D 349
12.72 XDWriteRead (10) command
The XDWriteRead (10) command requests that the target xor the data transferred (data-out) with the data on
the medium and return the resulting xor data (data-in). This is the equivalent to an XDWrite (10) command fol-
lowed by an XDRead (10) command with the same Logical Block Address and Transfer Length. This command
is only available on transport protocols supporting bidirectional commands.
Field definitions (listed alphabetically)
Control
See Section 11.2.1.6.
DPO (Disable Page Out)
1 No data is cached. The DPO bit is only meaningful if the RCD bit of Mode Select Page 8 is set false (caching
enabled).
Disable Write
0 The data transferred from the initiator is written to the medium after the xor operation is complete.
1 The data is not written to the medium.
FUA (Force Unit Access)
1 The Write command does 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.
Logical Block Address
The starting logical block address of the data to be affected by the xor operation.
Transfer Length
The number of logical blocks to be transferred to the XDWrite target for the xor operation. It also specifies the number of
blocks to be written to the medium after the xor operation.
Table 237: XDWriteRead (10) command (53h)
Bit
Byte
76543210
001010011
1
Reserved DPO FUA
Disable
Write
Reserved
2
3
4
5
(MSB)
Logical Block Address
(LSB)
6
Reserved
7 (MSB)
Transfer Length
8 (LSB)
9 Control
53h
Table
number
237
237
237
237
237
237