Re: discard synchronous on most SSDs?

Chris Murphy
2014-03-14T03:39:04Z

On Mar 13, 2014, at 8:11 PM, Marc MERLIN <marc@merlins.org> wrote:

> On Sun, Mar 09, 2014 at 11:33:50AM +0000, Hugo Mills wrote:
>> discard is, except on the very latest hardware, a synchronous command
>> (it's a limitation of the SATA standard), and therefore results in
>> very very poor performance.
>
> Interesting. How do I know if a given SSD will hang on discard?
> Is a Samsung EVO 840 1TB SSD latest hardware enough, or not? :)

smartctl -a or -x will tell you what SATA revision is in place. The queued trim support is in SATA Rev 3.1. I'm not certain if this requires only the drive to support that revision level, or both controller and drive.

Chris Murphy