Query regarding response of UNMAP command

Munjal Mistry munjal_mistry at mentor.com
Thu Feb 19 03:18:28 PST 2015


* From the T10 Reflector (t10 at t10.org), posted by:
* Munjal Mistry <munjal_mistry at mentor.com>
*
Hi,
I have a query regarding the response for UNMAP command when there is 
mismatch of "PARAMETER LIST LENGTH" (field of UNMAP command) with "UNMAP 
DATA LENGTH" or "UNMAP BLOCK DESCRIPTOR DATA LENGTH" (fields of unmap 
parameter list).  Here, Storage device is thin provisioning.
For example, host wants to transfer single block descriptor with UNMAP 
command. In this cases following values shall be driven:
PARAMETER LIST LENGTH= 'h18 (24),
UNMAP DATA LENGTH= 'h16 (22),
UNMAP BLOCK DESCRIPTOR DATA LENGTH= 'h10 (16).
Here, if host transmits other than 'h16 value for UNMAP DATA LENGTH 
field or other than 'h10 for UNMAP BLOCK DESCRIPTOR DATA LENGTH field, 
then which of the following behavior of device is correct:
(1) Device ignores it's value and unmap the logical blocks described 
with UNMAP block descriptor and sends GOOD response.
(2) Device ignores it's value and unmap the logical blocks described 
with UNMAP block descriptor and sends failure response.
(3) Device terminates the command and sends failure response.
If device sends the failure response, as per the 2nd and 3rd behavior 
then what would be the possible status, ASC and ASCQ for failure?
-- 
Warm Regards,
Munjal Mistry
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