From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Durgin Subject: Re: Ceph and KVM live migration Date: Sat, 30 Jun 2012 18:17:51 -0700 Message-ID: <4FEFA53F.4020503@inktank.com> References: <4FEF9CF1.6030008@bashkirtsev.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ob0-f174.google.com ([209.85.214.174]:36092 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751946Ab2GABRw (ORCPT ); Sat, 30 Jun 2012 21:17:52 -0400 Received: by obbuo13 with SMTP id uo13so5893428obb.19 for ; Sat, 30 Jun 2012 18:17:52 -0700 (PDT) In-Reply-To: <4FEF9CF1.6030008@bashkirtsev.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Vladimir Bashkirtsev Cc: ceph-devel@vger.kernel.org On 06/30/2012 05:42 PM, Vladimir Bashkirtsev wrote: > Dear all, > > Currently I testing KVMs running on ceph and particularly testing recent > cache feature. Performance is of course vastly improved but still have > occasional KVM hold ups - not sure who is at blame ceph of KVM. But I > will deal with it later. Right now I've got myself a question which I > could not get answered myself: if I do live migration of KVM while there > some uncommitted data in ceph cache will this cache be committed prior > cut-over to another host? Reading through the list I've got an > impression that it may be left uncommitted and thus it may cause data > corruption. I just would like a simple confirmation if code which > commits cache on cut-over to new host does exist and no data corruption > due to RBD cache+live migration should happen. > > Regards, > Vladimir QEMU does a flush on all the disks when it stops the guest on the original host, so there will be no uncommitted data in the cache. Josh