From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Choosing the right KVM version for production on CentOS 5.3 Date: Sun, 07 Jun 2009 09:44:21 +0300 Message-ID: <4A2B61C5.3010707@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: KVM To: Federico Simoncelli Return-path: Received: from mx2.redhat.com ([66.187.237.31]:46771 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752897AbZFGGo0 (ORCPT ); Sun, 7 Jun 2009 02:44:26 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: Federico Simoncelli wrote: > Hi all, > I'm trying to switch from xen to kvm. I already successfully installed > and tested kvm-84 on a CentOS 5.3 but before put it in production I'd > like some advices from you: > > 1) I'm trying to settle and use one version of kvm maybe backporting > some patches when needed. What version do you suggest me to use in a > production environment? > For production, use kvm-kmod-2.6.30-rc8 (and its updates), and qemu-kvm-0.10.5 (and its updates). > 2) I'm pretty much confused about kvm-x and qemu-kvm, anyway I used > kvm-84 with no problem and lately I'm testing qemu-kvm 0.10.5 with the > kvm-84 kernel module. Is this combination (kvm-84 kernel module and > qemu-kvm 0.10.5) right? Is there a better one? > kvm-xx are really development snapshots; they undergo testing but they don't get fixes backported. If you are interested in minimal churn and maximum stability, use the combination above. > 3) What is the difference between qemu-kvm 0.10.5 (on the kvm > sourceforge site) and qemu 0.10.5. Which one do you suggest me to use > in a production environment? > qemu-kvm-0.10.5 is qemu-0.10.5 with improved kvm integration (for example, smp) and a few additional features. Use qemu-kvm 0.10.5 for best performance and stability. > 4) I saw that the rpm packages for CentOS (provided by lfarkas.org) > are based on qemu 0.10.4, is there a reason? is it a very stable > release? I tried to contact Farkas but I had no reply yet. > No idea, I hope the packages will be updated soon. > The last question might be split in a new thread: > > 5) I tried to use qcow2 images with migration (storing them on gfs) > but the migration fails very frequently (mostly on heavy disk load). I > think the problem is that the new qemu-kvm (the -incoming one) reads > (or tries to read) the qcow2 headers before receiving the full ram > memory image and during the transfer time the qcow2 file get modified > by the old qemu-kvm (the dying one) which flushes the disk cache. Is > anyone else trying to let qcow2 work with migration? > qcow2 works with migration, there might be issues with GFS though. Can you try qemu-kvm 0.10.5 with qcow2 over NFS? If that works for you, we can try to debug the GFS issue. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.