Re: discard synchronous on most SSDs?

Chris Samuel
2014-03-15T05:25:12Z

[-- Attachment #1: Type: text/plain, Size: 962 bytes --]

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

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 482 bytes --]