Re: quotacheck speed

[Dave Chinner <david@fromorbit.com>]

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@fromorbit.com

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