From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id i5AFYm009604 for ; Thu, 10 Jun 2004 11:34:48 -0400 Received: from mail.ukfsn.org (s2.ukfsn.org [217.158.120.143]) by mx3.redhat.com (8.12.10/8.12.10) with ESMTP id i5AFYgXn014797 for ; Thu, 10 Jun 2004 11:34:42 -0400 Received: from localhost (lucy.ukfsn.org [127.0.0.1]) by mail.ukfsn.org (Postfix) with ESMTP id 6E870E6A8B for ; Thu, 10 Jun 2004 16:32:32 +0100 (BST) Received: from mail.ukfsn.org ([127.0.0.1]) by localhost (lucy.ukfsn.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 11717-05 for ; Thu, 10 Jun 2004 16:32:32 +0100 (BST) Received: from oak.dgreaves.com (modem-2300.putangitangi.dialup.pol.co.uk [81.78.200.252]) by mail.ukfsn.org (Postfix) with ESMTP id B533BE6A83 for ; Thu, 10 Jun 2004 16:32:31 +0100 (BST) Received: from ash.dgreaves.com.dgreaves.com ([10.0.0.126]) by oak.dgreaves.com with esmtp (Exim 4.20) id 1BYRbH-0007Ye-Mb for linux-lvm@redhat.com; Thu, 10 Jun 2004 16:36:19 +0100 Message-ID: <40C87F8A.7080304@dgreaves.com> Date: Thu, 10 Jun 2004 16:34:34 +0100 From: David Greaves MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM2 seems to chop performance by 33% References: <40C86F52.4090500@dgreaves.com> <200406101105.47606.StuartHarper@tampabay.rr.com> In-Reply-To: <200406101105.47606.StuartHarper@tampabay.rr.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development Thanks I'd tried that, but no real change. I started 1t 128k and also tried 64k, 256k :) (oh, and 1k) dd if=/dev/video_vg/video_lv of=/dev/null bs=4k count=256k 262144+0 records in 262144+0 records out 1073741824 bytes transferred in 24.130318 seconds (44497624 bytes/sec) dd if=/dev/md0 of=/dev/null bs=4k count=256k 262144+0 records in 262144+0 records out 1073741824 bytes transferred in 15.404947 seconds (69701105 bytes/sec) David PS wait 'til you see what I'm getting through Rieserfs on top of it! cu:/huge/editing/tmp# time dd if=dummy.deleteme of=/dev/null bs=4k count=256k 262144+0 records in 262144+0 records out 1073741824 bytes transferred in 31.627904 seconds (33949193 bytes/sec) so throughput down by a factor of 2... but 1 step at a time.... Stuart Harper wrote: >While doing backups of my LVM2 drive, I've found that setting the DD block >size to 4096 greatly improved my performance. Formerly, DDs on my 240G LVM >were taking 23hrs to complete with a block size of 512 or 1024. The same >volume now takes less than 2 hours with a block size of 4096. Large numbers >did not seem to increase DD speed. > >On Thursday 10 June 2004 10:25 am, David Greaves wrote: > > >>65Mb/s on the raid5 device >>44Mb/s on the lv >> >>Is this expected? >> >>Kernel 2.6.6 >> >>representative dd's: >> >>cu:/huge/editing/tmp# time dd if=/dev/video_vg/video_lv of=/dev/null >>bs=1024k count=4k >>David >> >> >_______________________________________________ >linux-lvm mailing list >linux-lvm@redhat.com >https://www.redhat.com/mailman/listinfo/linux-lvm >read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > > >