From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: below 10MB/s write on raid5 Date: Tue, 12 Jun 2007 13:16:38 -0400 Message-ID: <466ED4F6.5060204@tmr.com> References: <200706111446.55813.Dexter.Filmore@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200706111446.55813.Dexter.Filmore@gmx.de> Sender: linux-raid-owner@vger.kernel.org To: Dexter Filmore Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Dexter Filmore wrote: > I recently upgraded my file server, yet I'm still unsatisfied with the write > speed. > Machine now is a Athlon64 3400+ (Socket 754) equipped with 1GB of RAM. > The four RAID disks are attached to the board's onbaord sATA controller > (Sil3114 attached via PCI) > Kernel is 2.6.21.1, custom on Slackware 11.0. > RAID is on four Samsung SpinPoint disks, has LVM, 3 volumes atop of each XFS. > > The machine does some other work, too, but still I would have suspected to get > into the 20-30MB/s area. Too much asked for? > Increase your stripe cache size in /sys/block/mdX/md/stripe_cache_size. If you have a chunk size of 256, try setting the cache size to 8192 and see if your write performance ends up ~100MB/s or so. echo 8192 > /sys/block/mdX/md/stripe_cache_size Where "X" is your array name, of course. Note, larger values will help more, but it's definitely diminishing returns, so don't get carried away. There was a report of problems with size > 32768, I don't remember the details, so I would avoid that as well. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979