Re: discard synchronous on most SSDs?

[Chris Samuel <chris@csamuel.org>]

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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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