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216 Fibre Channel Interface Manual, Rev. D
12.13.1 Unit Attention page (00h)
The Unit Attention page is the last page reported by the drive. See your individual drive’s Product Manual, Vol-
ume 1, Mode Sense Data section, for a table showing codes that indicate which of these bits are changeable
by the host using the Mode Select command.
Field definitions (listed alphabetically)
IL (Inquiry Length)
1 The standard Inquiry data available to a host is limited to the 36 bytes required by the SCSI-2 specification.
0 148 bytes of standard Inquiry data are available. The Additional Length field in byte 4 of the Inquiry data is updated
to reflect the actual number of additional bytes available.
JIT (Just In Time)
These bits allow you to enable and disable certain seek speeds. JIT0 represents the fastest seek type used by the drive,
JIT1 represents the second fastest, JIT2 represents the third fastest, and JIT3 represents the slowest seek type.
You can use these bits to reduce acoustics by disabling the fastest seeks. This can also reduce power consumption (from
seek activity). These JIT settings only affect user read and write operations. Background drive operations and user seek
commands will always use the fastest seek type.
1 The drive is allowed to use this seek type in its seek speed algorithm.
0 The drive is not allowed to use this seek type in its seek speed algorithm.
Note. If all JIT bits are set to zero, the drive enables JIT0 only.
Page Code
00h Unit Attention page code.
Page Length
02h or 06h The length of the Unit Attention page (in bytes).
PM (Performance Mode)
This bit is used to control the drive’s cache management algorithm to allow best performance in different types of systems.
It is the initiator’s responsibility to determine which setting is best for that system.
1 The number of cache segments is fixed to the value set in mode page 8.
0 The drive will optimize the number of segments depending on the command activity observed by the drive. The
number of segments value (in mode page 8) is ignored.
Table 146: Unit Attention page (00h)
Bit
Byte
76543210
0PS0000000
Page Code (00h)
1
Page Length
2
PM
0
IL Unit Attn
0
Rnd Strict SCSI-2
Default Reserved
3
Reserved
Self
Seek
Reserved
Default
4 Reserved JIT3 JIT2 JIT1 JIT0
5
Reserved
6
Reserved
7
Reserved
Table
number
146
146
146
146
146