From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Segitz Subject: Re: Performance of a software raid 5 Date: Tue, 21 Apr 2009 02:10:49 +0200 Message-ID: References: <49ED096E.1000002@anonymous.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <49ED096E.1000002@anonymous.org.uk> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tue, Apr 21, 2009 at 1:46 AM, John Robinson wrote: > I would have thought it's because you're running in degraded mode and one in > 3 sectors is having to be regenerated from the parity. It still seems a bit > slow, though. i don't think that that is a problem. The data is there without redundancy so i can't see how there would be the need to calculate anything > I'm not quite sure whether I should be disappointed at my writes being so > slow. Certainly there's a lot of rattling during writing, which probably > indicates lots of seeks to write ext3's journal. But reads are roughly what > I expected, at about three times the single-disc throughput. 200 MB/s reads would be nice but i expected quite a bit more speed writing too. I know that you don't get an O(n) speedup but falling behind the normal performance of a single drive seems not okay. Johannes Btw.:The controller is on PCI-E so no bottleneck there