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Re: slow file creation with xfs on software raid5 - suggestions?

To: Jens Schmalzing <j.s@xxxxxx>
Subject: Re: slow file creation with xfs on software raid5 - suggestions?
From: Matt Stegman <matts@xxxxxxx>
Date: Fri, 2 Apr 2004 17:02:48 -0600 (CST)
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <hhwu4ya7t2.fsf@alsvidh.mathematik.uni-muenchen.de>
Sender: linux-xfs-bounce@xxxxxxxxxxx
Make your RAID5 chunk size larger than 4kB.  I'd suggest you start with
32kB chunks; I chose 256kB for my RAID5 over four Serial ATA disks.

# time tar jxf linux-2.4.24.tar.bz2

real    0m35.627s
user    0m27.480s
sys     0m5.170s
# time rm -rf linux-2.4.24

real    0m5.761s
user    0m0.000s
sys     0m2.440s
# xfs_info /home
meta-data=/home                  isize=256    agcount=25, agsize=1048576 blks
         =                       sectsz=4096
data     =                       bsize=4096   blocks=26214400, imaxpct=25
         =                       sunit=64     swidth=192 blks, unwritten=1
naming   =version 2              bsize=4096
log      =internal               bsize=4096   blocks=12800, version=2
         =                       sectsz=4096  sunit=1 blks
realtime =none                   extsz=65536  blocks=0, rtextents=0


-- 
Matt Stegman


On 2 Apr 2004, Jens Schmalzing wrote:

> Hi,
>
> I'm currently testing a small fileserver, using an array of SCA disks
> with xfs on top of software raid5.  The chunk size of the raid is set
> to 4k, as is the sector size for the xfs filesystem.  To be more
> precise, the file system was created with
>
> | # mkfs -t xfs -f -s size=4096 -l size=16384b /dev/md0
> | meta-data=/dev/md0               isize=256    agcount=32, agsize=5608052 
> blks
> |          =                       sectsz=4096
> | data     =                       bsize=4096   blocks=179457664, imaxpct=25
> |          =                       sunit=1      swidth=6 blks, unwritten=1
> | naming   =version 2              bsize=4096
> | log      =internal log           bsize=4096   blocks=16384, version=2
> |          =                       sectsz=4096  sunit=1 blks
> | realtime =none                   extsz=24576  blocks=0, rtextents=0
>
> While the setup performs well in general, I am a bit disappointed at
> the file creation speed - for example, unpacking a Linux kernel tree
> (a bit more than 200MB in a bit less than 20k files and directories)
> takes more than a minute and a half.  The same is true for removing
> the whole thing again.  On the other hand, reading is really fast.
>
> Any suggestions on tuning the file system or the software raid to
> obtain better performance?  I'm also open to suggestions involving a
> different file system altogether.
>
> Regards, Jens.
>
>



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