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 07:19:10 -0400 (EDT) Message-ID: References: <20070718110525.GF13772@boogie.lpds.sztaki.hu> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <20070718110525.GF13772@boogie.lpds.sztaki.hu> Sender: linux-raid-owner@vger.kernel.org To: Gabor Gombas 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, Gabor Gombas wrote: > On Wed, Jul 18, 2007 at 06:23:25AM -0400, Justin Piszcz wrote: > >> I recently got a chance to test SW RAID5 using 750GB disks (10) in a RAID5 >> on a 3ware card, model no: 9550SXU-12 >> >> The bottom line is the controller is doing some weird caching with writes >> on SW RAID5 which makes it not worth using. > > Did you use the settings documented in > http://www.3ware.com/KB/article.aspx?id=11050 ? Setting nr_requests and > the deadline scheduler doubled the seq write performance for me. Do you > have the latest firmware? Firmware updates can improve performance - at > least for RAID5/6; I somewhat doubt that they care about JBOD > performance that much... > > Gabor > > -- > --------------------------------------------------------- > MTA SZTAKI Computer and Automation Research Institute > Hungarian Academy of Sciences > --------------------------------------------------------- > For the HW RAID tests (2) at the bottom of the e-mail, no, I did not set nr_requests or use the deadline scheduler. For the SW RAID tests, I applied similar optimizations, I am probably not at the latest firmware. The main thing I wanted to use though was SW RAID because the card itself offers so many ports, however, with write speed being that slow I am not sure its a good idea. Justin.