--On 12 December 2013 01:16:09 +0100 Miroslav Lachman <[email protected]>
wrote:
Is TRIM working on gmirror?
I have FreeBSD 8.4-RELEASE-p1 amd64 GENERIC machine with 2x SSDs:
...
But there is a WARNING at boot:
WARNING: /ssd_db: TRIM flag on fs but disk does not confirm that it
supports TRIM
The filesystem is classic UFS2.
Is TRIM supported throught gmirror, or not?
I think 8.4 is way too old for this. I have a number of 9.2 boxes - and
even on those, TRIM doesn't propagate through gmirror *yet* (at the time,
which is a few months ago I seem to remember reading 'It should work soon'
- but 9.2 doesn't appear to).
You can use gstat to show if any calls to BIO_DELETE are being made - i.e.
gstat -d
On the systems here the 'd/s' (which afaik is 'BIO_DELETE/second') remains
stubbornly at zero :(
The flipside is with decent SSD's these days TRIM isn't quite so
important... Some may even argue that *not* issuing heaps of BIO_DELETE on
the I/O channel is actually faster - so long as the SSD has time to play
catchup and isn't pegged all the time, I think they may be right :-)
-Karl
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