From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Deegan Subject: Re: [Xen-devel] (strange idea) unfriendly migration Date: Mon, 1 Nov 2010 10:15:18 +0000 Message-ID: <20101101101518.GE11016@whitby.uk.xensource.com> References: <1288379241.2632.69.camel@home.desunote.ru> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Return-path: Content-Disposition: inline In-Reply-To: <1288379241.2632.69.camel@home.desunote.ru> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-users-bounces@lists.xensource.com Errors-To: xen-users-bounces@lists.xensource.com To: George Shuklin Cc: "xen-devel@lists.xensource.com" , "xen-users@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org Hi, At 20:07 +0100 on 29 Oct (1288382841), George Shuklin wrote: > Good day. > > As we all know, xen requires assist from VM to migrate it. If VM will > acts wrong during migration, it will crash, or behave strangely until > reboot (nice sample - default -xen kernel in lenny). > > We need to accept changes in domU during migration: other domain id, > new vbd/vif and so on. > > This fine until we talks about friendly VM. But if VM is not very > friendly? For example, VM's user can upgrade kernel to different -xen, > which one working fine with normal mode, but incompatible with > migration? (Pretty typical situation for any kind of cloud environment > or hosting). The user can break their VM's kernel in all sorts of other ways too. :) > If we create HVM-based overlay for PV-guest to keep thing unchanged, we > can make migration much simpler. Nice idea. I'm not sure it's better than just using HVM for the guest in the first place, though - that way the user can install pretty much any kernel they want. And the performance would be worse than either plain PV or plain HVM. Cheers, Tim. -- Tim Deegan Principal Software Engineer, XenServer Engineering Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)