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Re: df bigger than ls?

To: Eric Sandeen <sandeen@xxxxxxxxxxx>
Subject: Re: df bigger than ls?
From: Brian Candler <B.Candler@xxxxxxxxx>
Date: Thu, 8 Mar 2012 09:59:32 +0000
Cc: xfs@xxxxxxxxxxx
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On Thu, Mar 08, 2012 at 08:50:35AM +0000, Brian Candler wrote:
> Aha.  This may well be what is screwing up gluster's disk usage on a striped
> volume - I believe XFS is preallocating space which is actually going to end
> up being a hole!

Here is a standalone testcase.

$ for i in {0..19}; do dd if=/dev/zero of=testfile bs=128k count=1 seek=$[$i * 
12]; done
$ xfs_bmap testfile
testfile:
        0: [0..255]: 1465133392..1465133647
        1: [256..3071]: hole
        2: [3072..5119]: 1465136464..1465138511
        3: [5120..6143]: hole
        4: [6144..10239]: 1465139536..1465143631
        5: [10240..12287]: hole
        6: [12288..20479]: 1465145680..1465153871
        7: [20480..21503]: hole
        8: [21504..37887]: 1465154896..1465171279
        9: [37888..39935]: hole
        10: [39936..58623]: 1465173328..1465192015

I expected to see: 20 extents of 256 blocks and 19 holes of 2816 blocks.

Regards,

Brian.

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