326 Fibre Channel Interface Manual, Rev. D

12.59 Write (12) command

The Write (12) command requests that the disc drive write to the medium the data transferred by the initiator.

This command is implemented with the disc drive specific parameters listed in Table 221. Refer also to the

Write Caching section in the individual drive’s Product Manual, Volume 2, for information on write cache con-

trol.

Field definitions (listed alphabetically)
Control
See Control Bytes in 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 08h is set false (caching
enabled).
FUA (Force Unit Access)
1 The Write command will 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 08h is true.
Logical Block Address
The logical block at which the write operation begins, if RelAdr bit is zero (see RelAdr bit definition).
RelAdr (Relative Address)
This function is not supported by drives described in this manual.
Transfer Length
The number of contiguous logical blocks of data that are transferred. A Transfer Length of zero (0) indicates no logical
blocks are transferred. This condition is not considered an error and no data is written. Any other value indicates the num-
ber of logical blocks that are transferred.

Table 222: Write (12) command (AAh)

Bit
Byte
7654321 0
010101010
1000
DPO FUA 00
RelAdr
Reserved
2Logical Block Address (MSB)
3Logical Block Address
4Logical Block Address
5Logical Block Address (LSB)
6Transfer Length (MSB)
7Transfer Length
8Transfer Length
9Transfer Length (LSB)
10 Reserved
11 Control
AAh
Table
number
222
222
222
222
222
222