From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: Raid sync observations Date: Sun, 08 Jan 2006 13:18:47 -0500 Message-ID: <43C15787.1080304@tmr.com> References: <43A8B623.5060704@nighthawkrad.net> <20051221114912.GY10278@strugglers.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Gordon Henderson Cc: Sebastian Kuzminsky , linux-raid@vger.kernel.org List-Id: linux-raid.ids Gordon Henderson wrote: >On Wed, 21 Dec 2005, Sebastian Kuzminsky wrote: > > > >>>But how does the performance for read and write compare? >>> >>> >>Good question! I'll post some performance numbers of the RAID-6 >>configuration when I have it up and running. >> >> > >Post your hardware config too if you don't mind. I have one server with 8 >drives and for swap (Which it never does!) I created 2 x 4 disk RAID 6 >arrays (same partition on all disks) and gave them to the kernel with >equal priority > >Filename Type Size Used Priority >/dev/md10 partition 1991800 0 1 >/dev/md11 partition 1991800 0 1 > >md10 : active raid6 sdd2[3] sdc2[2] sdb2[1] sda2[0] > 1991808 blocks level 6, 64k chunk, algorithm 2 [4/4] [UUUU] > >md11 : active raid6 sdh2[3] sdg2[2] sdf2[1] sde2[0] > 1991808 blocks level 6, 64k chunk, algorithm 2 [4/4] [UUUU] > >/dev/md10: > Timing buffered disk reads: 64 MB in 0.66 seconds = 97.28 MB/sec > >/dev/md11: > Timing buffered disk reads: 64 MB in 0.95 seconds = 67.59 MB/sec > >md10 is an on-board 4-port SII SATA controller, md11 is 2 x 2-port SII >PCI cards. (Server is currently moderately loaded, so results are a bit >lower than usual > >Cue the must/must not swap on RAID arguments ;-) > I wouldn't swap on RAID-6... performance is importand, swap is tiny compared to disk size. I would go to 2GB partitions and four-way RAID-1, since fast swap in seems to make for better "feel" and write is cached somewhat. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979