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Re: suddenly slow writes on XFS Filesystem

To: Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>
Subject: Re: suddenly slow writes on XFS Filesystem
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 9 May 2012 17:04:51 +1000
Cc: Stefan Priebe <s.priebe@xxxxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
In-reply-to: <4FAA153D.1030606@xxxxxxxxxxxxxxxxx>
References: <4FA63DDA.9070707@xxxxxxxxxxxx> <20120507013456.GW5091@dastard> <4FA76E11.1070708@xxxxxxxxxxxx> <20120507071713.GZ5091@dastard> <4FA77842.5010703@xxxxxxxxxxxx> <4FA7FA14.6080700@xxxxxxxxxxxxxxxxx> <4FA82B07.1020102@xxxxxxxxxxxx> <4FAA153D.1030606@xxxxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Wed, May 09, 2012 at 01:57:01AM -0500, Stan Hoeppner wrote:
> On 5/7/2012 3:05 PM, Stefan Priebe wrote:
> > Am 07.05.2012 18:36, schrieb Stan Hoeppner:
> >> What I would suggest is doing an xfsdump to a filesystem on another LUN
> >> or machine, expand the size of this LUN by 50% or more (I gather this is
> >> an external RAID), format it appropriately, then xfsrestore.  This will
> >> eliminate your current free space fragmentation, and the 50% size
> >> increase will delay the next occurrence of this problem.  If you can't
> >> expand the LUN, simply do the xfsdump/format/xfsrestore, which will give
> >> you contiguous free space.
> > But this will only help for a few month or perhaps a year.
> So you are saying your backup solution will fill up an additional 2.3TB
> in less than a year?  In that case I'd say you have dramatically
> undersized your backup storage and/or are not using file compression to
> your advantage.  And you're obviously not using archiving to your
> advantage or you'd not have the free space fragmentation issue because
> you'd be dealing with much larger files.
> So the best solution to your current problem, and one that will save you
> disk space and thus $$, is to use a backup solution that makes use of
> both tar and gzip/bzip2.

Why use the slow method? xfsdump will be much faster than tar. :)


Dave Chinner

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