From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Hennerbichler Subject: Re: kvm + ceph performance issues Date: Mon, 11 Mar 2013 10:45:48 +0100 Message-ID: <513DA7CC.50208@risc-software.at> References: <513880C3.2030608@risc-software.at> <20130308083549.GA8810@stefanha-thinkpad.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: To: Stefan Hajnoczi Return-path: Received: from email.edvz.uni-linz.ac.at ([140.78.3.65]:61455 "EHLO email.uni-linz.ac.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752079Ab3CKJqA (ORCPT ); Mon, 11 Mar 2013 05:46:00 -0400 In-Reply-To: <20130308083549.GA8810@stefanha-thinkpad.redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/08/2013 09:35 AM, Stefan Hajnoczi wrote: > Please try using virtio-blk instead of IDE. there is no difference if I use virtio-blk. > If the guest still jerks try using the Linux rbd block driver instead of > QEMU -drive rbd:. I haven't used Ceph much but there should be > documentation on attaching a RADOS block device to your Linux host. > Tell QEMU to use the RADOS block device like a regular file (you are now > using the kernel driver instead of QEMU code to talk to the Ceph > cluster). This doesn't work yet on the linux-kernel with format 2 images. Format 2 is capable of read/write snapshots and cooler cloning-stuff. I need this for backup-reasons. > Please let us know the outcome. If you find that virtio-blk does not > make much difference but using the kernel rbd driver does, then this > suggests there is a bug in QEMU's block/rbd.c. I'm pretty sure there is, other ceph users reported the same problems that I've found. The ceph developers are looking into it. > Stefan Wolfgang