18 prefetch (10) command, Prefetch (10) command – Seagate Fibre Channel Interface User Manual
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Fibre Channel Interface Manual, Rev. D
12.18
Prefetch (10) command
The Prefetch (10) command requests that the drive read and transfer the specified logical blocks to the drive's
cache memory. No data shall be transferred to the initiator.
Table 169: PREFETCH (10) command (34h)
Field definitions (listed alphabetically)
Control
See Control Bytes in Section 11.2.1.6.
Immed (Immediate)
0
Status shall be returned after the operation is complete.
1
Status shall be returned as soon as the command descriptor block has been validated.
Logical Block Address
The logical block address field specifies the first logical block of the range of logical blocks for this command.
Operation Code
34h
The operation code for the Prefetch (10) command.
RelAdr (Relative Addressing)
This function is not supported by drives described in this manual.
Transfer Length
The Transfer Length field specifies the number of contiguous logical blocks of data that shall be transferred to the drive's
cache memory.
0
The contiguous logical blocks up to and including the last logical block of the logical unit shall be transferred to the
drive's cache memory.
Any value other than 0 indicates the number of logical blocks that shall be transferred. The drive may elect to not transfer
logical blocks that already are contained in the cache memory.
If the Immed bit is zero and the specified logical blocks were successfully transferred to the cache memory, the drive shall
return Condition Met status. If the Link bit (see Control Bytes in Section 11.2.1.6) is one, the drive shall return Intermediate–
Condition Met status.
If Immed is one and the unlocked cache memory has sufficient capacity to accept all of the specified logical blocks, the
drive shall return Condition Met status. If the Link bit is one, the drive shall return Intermediate–Condition Met status.
If Immed is one, and the unlocked cache memory does not have sufficient capacity to accept all of the specified logical
blocks, the drive shall return Good status. The drive shall transfer to cache memory as many logical blocks as will fit. If the
Link bit is one, the drive shall return Intermediate status.
Bit
Byte
7
6
5
4
3
2
1
0
0
Operation Code (34h)
1
Reserved
Immed
RelAdr
2
3
4
5
(MSB)
Logical Block Address
(LSB)
6
Reserved
7
(MSB)
Transfer Length
8
(LSB)
9
Control
34h
Table
number