Seagate Fibre Channel Interface - Manual (Page 282)

268 Fibre Channel Interface Manual, Rev. D
12.24 Read (16) command (88h)
The Read (16) command requests that the target transfer data to the initiator.
Table 174: Read (16) command (88h)
Field definitions (listed alphabetically)
Control
See Control Bytes in 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.
1
The disc drive assigns the logical blocks accessed by this command the lowest priority for being fetched into or
retained by the cache. The host knows the logical blocks accessed by the command are not likely to be accessed
again in the near future and should not be put in the cache memory nor retained by the cache memory.
0 The host expects that logical blocks accessed by this command are likely to be accessed again in the near future.
FUA (Force Unit Access)
1
The target accesses the media in performing the command prior to returning Good status. Read commands access
the specified logical blocks from the media (i.e., the data is not directly retrieved from the cache). In the case where
the cache contains a more recent version of a logical block than the media, the logical block is first written to the
media.
Bit
Byte
7 6 5 4 3 2 1 0
0 1 0 0 0 1 0 0 0
1 0 0 0
DPO FUA
0 0
RelAdr
Reserved
2
Logical Block Address (MSB)
3
Logical Block Address
4
Logical Block Address
5
Logical Block Address
6
Logical Block Address
7
Logical Block Address
8
Logical Block Address
9
Logical Block Address (LSB)
10
Transfer Length (MSB)
11
Transfer Length
12
Transfer Length
13
Transfer Length (LSB)
14
Reserved
15
Control
Table
number
174
174
174