Re: discard synchronous on most SSDs?

[Chris Samuel <chris@csamuel.org>]

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On Fri, 14 Mar 2014 03:57:41 PM Martin K. Petersen wrote:

> The fact that the drive reports compliance with a certain version of
> SATA does not in any way imply that it implements all commands defined
> in that specification.

It looks like drives that do support it can be detected with the kernel helper 
function ata_fpdma_dsm_supported() defined in include/linux/libata.h.

I wonder if it would be possible to use that knowledge to extend the 
smartctl's --identify functionality to report this?

Not even all drives that implement it do so correctly, the kernel has a 
blacklist of drives that don't and currently lists just two:

       /* devices that don't properly handle queued TRIM commands */
       { "Micron_M500*",·      ·       NULL,·  ATA_HORKAGE_NO_NCQ_TRIM, },
       { "Crucial_CT???M500SSD*",·     NULL,·  ATA_HORKAGE_NO_NCQ_TRIM, },

cheers,
Chris
-- 
 Chris Samuel  :  http://www.csamuel.org/  :  Melbourne, VIC


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