Re: Software RAID and TRIM

On 28 June 2011 16:31, Tom De Mulder [off-list ref] wrote:

Hi,


I'm investigating SSD performance on Linux, in particular for RAID devices.

As I understand it—and please correct me if I'm wrong—currently software
RAID does not pass through TRIM to the underlying devices. TRIM is essential
for the continued high performance of SSDs, which otherwise degrade over
time.

I don't think there would be any harm in this command being passed through
to underlying devices if they don't support it (they would just ignore it),
and if they do it would make high-performance software RAID of SSDs a
possibility.


Is this something that's in the works?



Many thanks,

--
Tom De Mulder [off-list ref] - Cambridge University Computing Service
+44 1223 3 31843 - New Museums Site, Pembroke Street, Cambridge CB2 3QH
-> 28/06/2011 : The Moon is Waning Crescent (22% of Full)

IIRC md can already pass TRIM down, but I think the filesystem needs
to know about the underlying architecture, or something, for TRIM to
work in RAID. There's numerous discussions on this in the archives of
this mailing list.

/M
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