Re: df bigger than ls?

Brian Candler
2012-03-08T09:59:34Z

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.