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Re: quotacheck speed

To: Arkadiusz Miśkiewicz <arekm@xxxxxxxx>
Subject: Re: quotacheck speed
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 14 Feb 2012 10:42:35 +1100
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <201202131909.50605.arekm@xxxxxxxx>
References: <201202122201.07649.arekm@xxxxxxxx> <20120212234425.GA23625@xxxxxxxxxxxxx> <201202131909.50605.arekm@xxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Mon, Feb 13, 2012 at 07:09:50PM +0100, Arkadiusz Miśkiewicz wrote:
> On Monday 13 of February 2012, Christoph Hellwig wrote:
> > On Sun, Feb 12, 2012 at 10:01:07PM +0100, Arkadiusz Mi??kiewicz wrote:
> > > Hi,
> > > 
> > > When mounting 800GB filesystem (after repair for example) here quotacheck
> > > takes 10 minutes. Quite long time that adds to whole time of filesystem
> > > downtime (repair + quotacheck).
> > > 
> > > I wonder if quotacheck can be somehow improved or done differently like
> > > doing it in parallel with normal fs usage (so there will be no downtime)
> > > ?
> > 
> > I think the best idea to improve the performance in case you did a
> > repair is to integrate the quotacheck code into repair.  It's fairly
> > simple given that quotacheck simply walks all inodes and adds their
> > space usage to the correct user/group/project, and given that repair
> > already walks all inodes, and checks their block maps it does most of
> > that work already.
> 
> That would be interesting and probably make 
> 
> > The only downside would be that the memory usage
> > of repair increases a bit by keeping the dquots in memoryb, but even
> > for your 130000 dquot setup that would add about 100 bytes * 130000
> > please a bit of in-memory metadata (less than 20MB total) of memory
> > usage, so it probably is a good tradeoff.
> 
> > 
> > In what cases do you regularly run quotacheck when you did not do
> > a repair first?
> 
> I don't initiate quotacheck manually. AFAIK internal xfs quotacheck happens 
> in 
> two cases here:
> 1) repair->mount
> 2) filesystem has quotacheck done properly some time ago -> umount -> mount-
> >oops/reset/something like that happens while mounting -> new mount

So you'd like both quotacheck to be sped up and repair
to do it as well? ;)

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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