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 redhat com de la part de Rene Salmon
Date: mer. 08/08/2007 22:21
À: ext3-users redhat com
Objet : Poor ext3 performance on RAID array
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.