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Fibre Channel Interface Manual, Rev. D 313
12.50 Start/Stop Unit command
The Start/Stop Unit command requests that the target enable the logical unit for further operations (start), or
stop spindle rotation (stop).
The disc drive is able to execute the following commands when the drive spindle is not rotating, or in a simu-
lated stopped condition.
The remaining commands (see SCSI Interface commands supported section in individual drive’s Product Man-
ual for list of all commands supported) cannot be executed until after the drive has spindled up. If the disc drive
receives one of these commands before it can be executed, a Check Condition status is returned (with sense
key of Not Ready). The initiator closes the loop after a Start Unit is commanded. The disc drive arbitrates for
the loop when the unit is up to speed and Ready or when operation is initiated if the Immed bit is 1.
Field definitions (listed alphabetically)
Control
See Control Bytes in Section 11.2.1.6.
Immed (Immediate)
0 Status is returned after the operation is completed.
1 Status is returned as soon as the operation is initiated.
Start
1 Requests that the logical unit be made ready for use.
0 Requests that the drive to either actually stop the spindle or to simulate the drive spindle stopped condition. In this
latter situation the drive spindle actually continues to spin and the drive reports Not Ready in response to media
access commands. Power consumption is as when in idle mode. The type of stop implemented is given in the drive
Product Manual.
Table 213: Start/Stop Unit command (1Bh)
Bit
Byte
76543210
00001 1011
10000000
Immed
Reserved
200000000
300000000
40000000Start
5
Control
1Bh
•Test Unit
Ready
• Request
Sense
• Inquiry
•Reserve
• Release
• Motor
Start
• Receive
Diagnostic
Results
• Write Buffer
• Read
Buffer
Table
number
213
213
213