Re: discard synchronous on most SSDs?

Chris Samuel
2014-03-15T06:49:04Z

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On Sat, 15 Mar 2014 04:25:05 PM Chris Samuel wrote:

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

After reading the SATA 3.1 spec I believe that smartctl *can* indicate if a
drive claims to support SATA 3.1 NCQ TRIM, thus:

$ sudo smartctl --identify /dev/sdb | fgrep 'Trim bit in DATA SET MANAGEMENT'
169 0 1 Trim bit in DATA SET MANAGEMENT command supported
$

If that command returns nothing then it's not reported as supported (and I've
tested that). You can get the same info with hdparm -I.

Of course, as Martin said, that doesn't necessarily mean the kernel is using
that reported ability.

My puzzle now is that I have two SSD drives that report supporting NCQ TRIM
(one confirmed via product info) but report only supporting SATA 3.0 not 3.1.

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

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