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Re: Strange delete performance using XFS

To: Thomas Kaehn <tk@xxxxxxxxxxx>
Subject: Re: Strange delete performance using XFS
From: Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>
Date: Wed, 4 Apr 2007 10:24:42 -0400 (EDT)
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20070404142142.GG18320@xxxxxxxxxxxxxxxxxx>
References: <20070404130535.GE18320@xxxxxxxxxxxxxxxxxx> <Pine.LNX.4.64.0704040928110.7309@xxxxxxxxxxxxxxxx> <20070404134724.GF18320@xxxxxxxxxxxxxxxxxx> <Pine.LNX.4.64.0704040957120.7309@xxxxxxxxxxxxxxxx> <Pine.LNX.4.64.0704041012330.7309@xxxxxxxxxxxxxxxx> <20070404142142.GG18320@xxxxxxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx


On Wed, 4 Apr 2007, Thomas Kaehn wrote:

Hi Justin,

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

1. Six 400GB SATA drives using SW RAID5:
real    6m24.411s
user    0m43.097s
sys     2m17.350s


The removals:
The benchmark:
$ time rm -rf test

1. Six 400GB SATA drives using SW RAID5:
real    0m33.996s
user    0m0.057s
sys     0m8.101s

thanks for your bechmark. To my mind this clearly shows that my
setup is wrong at some point. I'll try again with your mount options.

Ciao,
Thomas
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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.

Justin.
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