User Manual

SCSI Commands Reference Manual, Rev. J 223
www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)
3.49 START STOP UNIT command
The START STOP UNIT command (see table 194) requests that the device server change the power condition of the logical unit
(see
SBC-4) or load or eject the medium. This includes specifying that the device server enable or disable the direct-access block
device for medium access operations by controlling power conditions and timers.
If a START STOP UNIT command is being processed by the device server, and a subsequent START STOP UNIT command for which
the CDB is validated requests that the logical unit change to a different power condition than was specified by the START STOP
UNIT command being processed, then the device server shall terminate the subsequent START STOP UNIT command with
CHECK CONDITION status with the sense key set to NOT READY and the additional sense code set to LOGICAL UNIT NOT READY,
START STOP UNIT COMMAND IN PROGRESS.
IMMED (Immediate) bit
0 If the immediate (IMMED) bit is set to zero, then the device server shall return status after the operation is completed.
1 If the IMMED bit set to one, then the device server shall return status as soon as the CDB has been validated.
POWER CONDITION field and POWER CONDITION MODIFIER field
The combinations of values in the POWER CONDITION field and POWER CONDITION MODIFIER field are defined in table 195. If the POWER
CONDITION field is supported and is set to a value other than 0h, then the START and LOEJ bits shall be ignored.
Table 194 START STOP UNIT command
Bit
Byte
7 6 5 4 3 2 1 0
0
OPERATION CODE (1Bh)
1
Reserved IMMED
2
Reserved
3
Reserved POWER CONDITION MODIFER
4
POWER CONDITION Reserved NO_ FLUSH LOEJ START
5
CONTROL
Table 195 POWER CONDITION field and POWER CONDITION MODIFIER field
POWER
CONDITION
POWER CONDITION
Name
POWER CONDITION
MODIFIER value
Description
0h
START_VALID
0h
Process the START and LOEJ bits.
1h
ACTIVE
0h
Cause the logical unit to transition to the active power condition (see SPC-5).
2h
IDLE
0h
Cause the logical unit to transition to the idle_a power condition (see SPC-5).
1h
Cause the logical unit to transition to the idle_b power condition (see SPC-5).
Cause the logical unit to transition to the idle_c power condition (see SPC-5).
3h
STANDBY
0h
Cause the logical unit to transition to the standby_z power condition (see SPC-5).
1h
Cause the logical unit to transition to the standby_y power condition (see SPC-5).
5h
Obsolete
0h to Fh
Obsolete
7h
LU_CONTROL
0h
Initialize and start all of the idle condition timers that are enabled (see SPC-5), and
initialize and start all of the standby condition timers that are enabled (see SPC-5).