Re: Can somebody explain this? du & ls showing different sizes

From: Patrick O'Callaghan <pocallaghan@xxxxxxxxx>
Subject: Re: Can somebody explain this? du & ls showing different sizes
To: fedora-list@xxxxxxxxxx
Date: Monday, February 16, 2009, 8:45 AM
 

On Mon, 2009-02-16 at 07:13 +0000, Vijay Gill wrote:
> 2009/2/16 Patrick O'Callaghan <pocallaghan@xxxxxxxxx>:
> > On Sun, 2009-02-15 at 23:45 +0000, Vijay Gill wrote:
> >>  > That could be because you're using XFS.
> >> >
> >> > poc
> > [...]
> >> Thanks but how does that statement explain the behaviour I am
seeing?
> >
> > I'm
 reaching here, but since XFS uses allocation strategies
different
> > from the more familiar ext3 system, I wondered if 'du' could
in some
> > circumstances report larger numbers than "normal".
> >
> > Apologies if I'm raving.
> >
> > poc
> >
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> 
> You are spot on Pat. XFS allws you to pre-allocate contiguous area of
> disk for a file when it is opened for writing data. This is determined
> by allocsize parameter during mount and is used foe reducing
> fragmentation(fragmentation in Linux? yes siree, it does happen in
> Linux too).
> 
> In my case I have provided 1M
 which is far much less than 512M which
> XFS is pre-allocating. This is what caught my eye.

It's nice to have one's intuition confirmed once in a while :-)

poc

Hi Poc

Where is the overallocation parameter stored? 

Poc, I appreciate your expertise in the answers, but when you answer something about Linux,
note that I have not your ideas of where to look for settings.
Therefore, I am sure readers would like a hint about the directory/file in which this info
is stored.

Thanks and have a good weekend.

Leslie