Poor ext3 performance on RAID array
rsalmon74 at gmail.com
Wed Aug 8 20:53:43 UTC 2007
Thanks for the reply. I tried using the -E stride=X option as follows:
mkfs.ext3 -b4096 -Tlargefile4 -E stride=640 /dev/dm-1
and got the same results around 50 MBytes/sec. Maybe I have the wrong
number for stride so here is the math for that:
Configure the filesystem for a RAID array
stripe-size filesystem blocks per stripe.
Here is some more detail on the RAID array.
RAID level : 5 (10 drives + 1 parity)
Chunk Size : 256 KB
Stripe Size : 2560 KB (10 drives * 256KB)
stride=640 * 4096(byte blocks) = 2560KB
I will try other stride options but they don't seem to change much.
On 8/8/07, GARDAIS Ionel <Ionel.Gardais at tech-advantage.com> wrote:
> Hi Rene,
> You should try to add the "-E stride=X" option to the mkfs command line.
> Where X is expalined in the man page.
> This will basically map ext3 "blocks" on the RAID stripe size.
> -------- Message d'origine--------
> De: ext3-users-bounces at redhat.com de la part de Rene Salmon
> Date: mer. 08/08/2007 22:21
> À: ext3-users at redhat.com
> Objet : Poor ext3 performance on RAID array
> Hi list,
> I am having some strange performance issues with ext3 and I am hoping to
> get some advice/hints on how to make this better. First some background
> on the setup.
> We have a RAID 5 array 10+1+1 with one LUN. That is 10 SATA drives one
> parity drive and one dedicated spare. The LUN is about 6.5TB.
> Using a 2Gbit/sec fiber channel card I can do some dd writes to the raw
> device and get speeds close to 200Mbytes/sec which is more or less the
> max the card can do.
> Next I create an xfs file system on the LUN and do a dd to xfs and get
> speeds close to 150Mbytes/sec.
> I want to use ext3 not xfs so next I put ext3 on the lun. Now when I do
> the dd to the ext3 lun I get 25-50Mbytes/sec depending on whether I have
> the Raid controller cache turned on or off. Getting 50MBytes/sec with
> the raid controller cache turned off.
> I know that ext3 should perform better so I must be doing something
> wrong. Here is my mkfs.ext3
> mkfs.ext3 -b4096 -Tlagefile4 /dev/dm-0
> Thanks in advanced for any help on this.
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