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Re: Files appear too big in `du`

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: Files appear too big in `du`
From: Matthias Schniedermeyer <ms@xxxxxxx>
Date: Thu, 12 May 2011 12:01:53 +0200
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20110510153300.GA5764@xxxxxxx>
References: <20110510105700.GA20307@xxxxxxx> <20110510131705.GE19446@dastard> <20110510153300.GA5764@xxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On 10.05.2011 17:33, Matthias Schniedermeyer wrote:
> 
> > > Any idea how to debug this, or is this a known bug and waiting a few 
> > > days for 2.6.39 should fix this?
> > 
> > It doesn't appear to be doing anything wrong from your description.
> > Remember that XFS is optimised for high end storage and server
> > configurations and workloads, not typical desktop usage...
> 
> I would call it a regression.
> I reguarly follow copying/downloading with `du`, the speculative
> preallocation makes that more or less useless. Especially downloading 
> someting big from the internet which @ 231kb/s isn't exactly fast and 
> shows identical `du`s for increasingly longer periods of time.
> (Or "--apparent-size" should be made default, but that falls short with 
> sparse-files)
> 
> IMHO `du`/`ls -l` should not be able to 'see' the speculative 
> preallocation.


After digging into the log of v2.6.37..v2.6.38 i stumbled upon:

- snip -
    The allocsize mount option turns off the dynamic behaviour and fixes
    the prealloc size to whatever the mount option specifies. i.e. the
    behaviour is unchanged.
- snip -

I think Documentation/filesystems/xfs.txt is in need of an update. All 
that information in the commit-log is a little "out-of-reach" for most 
people.






Bis denn

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Real Programmers consider "what you see is what you get" to be just as 
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