Date: Mon, 30 Dec 2013 23:24:52 +0000 From: Karl Pielorz <kpielorz_lst@tdx.co.uk> To: Miroslav Lachman <000.fbsd@quip.cz>, freebsd-geom@FreeBSD.org Subject: Re: Is TRIM working with gmirror? Message-ID: <18C59233568D3A475FF0D843@study64.tdx.co.uk> In-Reply-To: <52A90049.7050001@quip.cz> References: <52A90049.7050001@quip.cz>
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--On 12 December 2013 01:16:09 +0100 Miroslav Lachman <000.fbsd@quip.cz> 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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