Behavior of SCSI device for START STOP UNIT command

Munjal Mistry munjal_mistry at mentor.com
Thu Nov 20 02:06:01 PST 2014


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Hello All,
I have a query regarding the device behavior for changing the power 
condition during on-going read/write operation.
*Scenario:*
Suppose, the device is in active power mode and logical unit 0 is 
processing write command and logical unit 1 is processing read command. 
In between this process, host sends START STOP UNIT command which 
requests to change power mode to sleep/power down mode, followed by READ 
CAPACITY (10) command.
In this case, which behavior of device is correct?
(1) Device will wait for the READ and WRITE commands to completion and 
then move to pre-sleep/pre-power down mode and sends CHECK CONDITION 
status for READ CAPACITY (10) command.
(2) Device will send response with GOOD status for READ CAPACITY (10) 
command and wait for completion of READ-WRITE command and then move to 
pre-sleep/pre-power down mode
(3) Device stops processing READ-WRITE command and sends CHECK CONDITION 
status for READ-WRITE command and move to pre-sleep/pre-power down mode. 
Then device sends CHECK CONDITION status for READ CAPACITY (10) command.
In-case any of the above mentioned behavior is not correct then it would 
be great if you could let me know the expected behavior of the device.
Thanks in advance.
-- 
Warm Regards,
Munjal Mistry



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