From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keld =?iso-8859-1?Q?J=F8rn?= Simonsen Subject: Re: Raid6 write performance Date: Mon, 19 Jan 2009 13:48:37 +0100 Message-ID: <20090119124837.GC23623@rap.rap.dk> References: <49742E74.9090502@rabbit.us> <8CB482475EFC01A-17F0-256E@webmail-dx12.sysops.aol.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Return-path: Content-Disposition: inline In-Reply-To: <8CB482475EFC01A-17F0-256E@webmail-dx12.sysops.aol.com> Sender: linux-raid-owner@vger.kernel.org To: thomas62186218@aol.com Cc: rabbit+list@rabbit.us, linux-raid@vger.kernel.org List-Id: linux-raid.ids On Mon, Jan 19, 2009 at 03:10:01AM -0500, thomas62186218@aol.com wrote: > > I tested RAID 5 and RAID 6 with 12 x 15K SAS drives on Ubuntu 8.04 > 64-bit and found their performance to be about the same. I used 256 K > chunk size, v1.0 superblocks, stripecachesize of 16384, and readahead > of 65536. > > RAID 5 reads: 774 MB/sec > RAID 5 writes: 585 MB/sec > > RAID 6 reads: 742 MB/sec > RAID 6 writes: 559 MB/sec > > My CPU utilization remains under 10% though during writes, and I'm > wondering what can be done to get write performance closer to read > performance. I have dual quad-core CPUs so there's plenty of CPU to go > around. Any ideas on that front? Seems like it is the same equipment that you also did the raid10,f2 tests for. I think it would be interesting to have a consolidated list of performance comparisons, when you have completed your tweakings. Is that part of your plan? best regards keld