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Fibre Channel Interface Manual, Rev. D 353
12.75 XPWrite (32) command
The XPWrite (32) command requests that the target xor the data transferred with the data on the medium and
then write the xor data to the medium.
If the logical unit is reserved, a reservation conflict occurs when a XPWrite command is received from an initia-
tor other than the one holding the logical unit reservation. The command is rejected with Reservation Conflict
status if the reservation conflict is due to a logical unit reservation. The XPWrite command is evaluated for
extent reservation conflicts. XPWrite commands with a reservation conflict is terminated with Check Condition
status and the sense key is set to Data Protect with the appropriate additional sense code for the condition if
any part of the XPWrite operation is prohibited by an extent reservation.
Field definitions (listed alphabetically)
Additional CDB Length
The Additional CDB Length field indicates the number of additional CDB bytes. This value in the Additional CDB Length
field shall be a multiple of 4. If the number of CDB bytes delivered by the service delivery subsystem is not sufficient to con-
tain the number of bytes specified by the Additional CDB Length field, the command shall be terminated with a Check Con-
dition status. The sense key shall be set to Illegal Request and the additional sense code shall be set to Invalid Field in
CDB.
Control
See Section 11.2.1.6.
DPO (Disable Page Out)
The DPO bit is used to control replacement of logical blocks in the cache memory when the host has information on the
future usage of the logical blocks.
Table 240: XPWrite (32) command (7Fh)
Bit
Byte
76543210
001111111
1
Control
2
:
6
Reserved
7
Additional CDB Length (18h)
8 (MSB)
Service Action (0006h)
9 (LSB)
10 Reserved DPO FUA Reserved
11
Reserved
12
:
19
(MSB)
Logical Block Address
(LSB)
20
:
27
Reserved
28
:
31
(MSB)
Transfer Length
(LSB)
7Fh
Table
number
240
240
240