Re: Strange delete performance using XFS

Justin Piszcz
2007-04-04T20:45:12Z

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On Wed, 4 Apr 2007, Thomas Kaehn wrote:

> Hi Justin,
>
> On Wed, Apr 04, 2007 at 10:24:42AM -0400, Justin Piszcz wrote:
>>> On Wed, Apr 04, 2007 at 10:12:48AM -0400, Justin Piszcz wrote:
>>>> On Wed, 4 Apr 2007, Justin Piszcz wrote:
>>>>> On Wed, 4 Apr 2007, Thomas Kaehn wrote:
>>>>> $ time for i in `seq 1 100000`; do dd if=/dev/zero of=$i bs=1k count=20
>>>>>> /dev/null 2>&1; done
>>>>>
>> My guess is mkfs.xfs cannot optimzie for your array like it can with a SW
>> RAID device because it cannot see what is undereath it. Have you tried
>> making a SW RAID? I also use optimized parameters for my SW RAID1/5 as
>> well FYI.
>
> I guess this might be the problem. I've already tried to alter
> the stripe unit to match the RAID stripe size: "-d su=64k,sw=2 -l su=64k".
>
> Maybe the 3ware controller can't deal with the kind of read and write
> patterns needed by XFS. But in this case other people should have
> realized similar problems.
>
> On a different system with a 3ware 9500S-4LP using 4 disks as RAID5
> setup I get a better (but not really good) result for delete
> performance (I've taken only 50000 files in this case as the system's
> CPU is much slower):
>
> | # time for i in `seq 1 50000`; do dd if=/dev/zero of=$i
> | bs=1k count=20 >/dev/null 2>&1; done
> |
> | real 18m21.643s
> | user 0m55.727s
> | sys 3m12.140s
> | backup:/srv/x# cd ..
> | backup:/srv# rm -rf x
> |
> | # time rm -rf x
> |
> | real 5m7.845s
> | user 0m0.160s
> | sys 0m11.369s
>
>
> Ciao,
> Thomas
> --
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What do you get with ext3 when using time bash -c 'rm -f file; sync'