From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Re: help with bad performing raid6 Date: Mon, 27 Jul 2009 21:44:41 +0100 Message-ID: <4A6E11B9.3080908@anonymous.org.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Jon Nelson Cc: LinuxRaid List-Id: linux-raid.ids On 27/07/2009 20:19, Jon Nelson wrote: > I have a raid6 which is exposed via LVM (and parts of which are, in > turn, exposed via NFS) and I'm having some really bad performance > issues [...] Probably the first thing to do is to isolate the problem. First up, I'd say run bonnie++ against the filesystem locally, then you can eliminate the possibility of NFS or networking causing problems. Then, have you any spare space on the LVM VG with which you could try another filesystem? > If I look at the load on the server the top process is > md0_raid5 (the raid6 process for md0, despite the raid5 in the name). > The load hovers around 8 or 9 at this time. You say it's the top process, but is it using any CPU, or just blocked waiting for the discs? Cheers, John.