From mboxrd@z Thu Jan 1 00:00:00 1970 From: Justin Piszcz Subject: Re: Software RAID5 Horrible Write Speed On 3ware Controller!! Date: Wed, 18 Jul 2007 12:26:29 -0400 (EDT) Message-ID: References: <469DF039.4040906@theendofthetunnel.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <469DF039.4040906@theendofthetunnel.de> Sender: linux-raid-owner@vger.kernel.org To: Hannes Dorbath Cc: linux-ide-arrays@lists.math.uh.edu, xfs@oss.sgi.com, linux-raid@vger.kernel.org, linux@vger.kernel.org List-Id: linux-raid.ids On Wed, 18 Jul 2007, Hannes Dorbath wrote: > On 18.07.2007 12:23, Justin Piszcz wrote: >> I am sure one of your questions is, well, why use SW RAID5 on the >> controller? Because SW RAID5 is usually much faster than HW RAID5, at >> least in my tests: > > Though that's no answer to your question, I really can't confirm that. I'm > running a 3Ware 9650 with 8x 7200 SATAs in HW RAID 6. Writes are between > 340-360MB/sec and reads peak at 430-450MB/sec. That seems to be the absolute > possible maximum those drives can deliver. The card even seems to do some > really smart stuff, as the read speed is in excess of the physical raw speed > of 6 drives. > > You have done the usual settings, 3Ware recommends? > > echo 64 > /sys/block/sda/queue/max_sectors_kb > echo 512 > /sys/block/sda/queue/nr_requests > echo "deadline" > /sys/block/sda/queue/scheduler > blockdev --setra 16384 /dev/sdX > > Have you set the correct su,sw options for XFS? > > > -- > Regards, > Hannes Dorbath > I will try these options during future testing and re-visit the speeds of regular HW RAID5, thanks! I know they are part of the 3ware doc and I need to re-bench with these.