<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <META NAME="Generator" CONTENT="MS Exchange Server version 6.5.7638.1"> <TITLE>RE : RE : Poor ext3 performance on RAID array</TITLE> </HEAD> <BODY>  stride is the chunk size of your raid whatever the number of physical disks composing the RAID array. So for 256k chunks with a block size of 4k, stride should be 256/4 = 64 instead of 640. Maybe it will help. Ionel -------- Message d'origine-------- De: Rene Salmon [<A HREF="mailto:rsalmon74@gmail.com">mailto:rsalmon74@gmail.com</A>] Date: mer. 08/08/2007 22:53 À: GARDAIS Ionel Cc: ext3-users@redhat.com Objet : Re: RE : Poor ext3 performance on RAID array Hi, 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: stride=stripe-size Configure the filesystem for a RAID array with 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. Thanks Rene On 8/8/07, GARDAIS Ionel <Ionel.Gardais@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. > > Ionel > > > -------- 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 > > 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. > > Rene > > </BODY> </HTML>