From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: Raid over 48 disks Date: Thu, 20 Dec 2007 20:53:56 -0500 Message-ID: <476B1CB4.2070404@tmr.com> References: <00EF99B2-3BCC-4D75-BC75-8F256B0A2476@gmail.com> <476820B0.9010200@ph.tum.de> <476837F6.7050404@ph.tum.de> <476936DD.40301@tmr.com> <476A9CE4.4010107@ph.tum.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <476A9CE4.4010107@ph.tum.de> Sender: linux-raid-owner@vger.kernel.org To: Thiemo Nagel Cc: Justin Piszcz , Norman Elton , linux-raid@vger.kernel.org List-Id: linux-raid.ids Thiemo Nagel wrote: > Bill Davidsen wrote: >>> 16k read 64k write >>> chunk >>> size RAID 5 RAID 6 RAID 5 RAID 6 >>> 128k 492 497 268 270 >>> 256k 615 530 288 270 >>> 512k 625 607 230 174 >>> 1024k 650 620 170 75 >>> >> >> What is your stripe cache size? > > I didn't fiddle with the default when I did these tests. > > Now (with 256k chunk size) I had > > # cat stripe_cache_size > 256 > > but increasing that to 1024 didn't show a noticeable improvement for > reading. Still around 550MB/s. You can use blockdev to raise the readahead, either on the drives or the array. That may make a difference, I use 4-8MB on the drive, more on the array depending on how I use it. > > Kind regards, > > Thiemo > -- Bill Davidsen "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark