Hi, I am trying to do live migration from Xen 4.1 to 4.2 which is working. But not the other way around. Somewhere in mailing lists I read 4.2 -> 4.1 migration is not supported. So my question is what kind of live migration support that xen team is seeing for the future across versions? For example what are plans to support live migration from 4.2 --> 4.3. ? And also how about supporting from 4.3 ---> 4.2 and so on. Thanks Siva _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
On Thu, 2013-04-18 at 16:41 +0100, Siva Palagummi wrote:> Hi, > > > I am trying to do live migration from Xen 4.1 to 4.2 which is working. > But not the other way around. Somewhere in mailing lists I read 4.2 > -> 4.1 migration is not supported. So my question is what kind of live > migration support that xen team is seeing for the future across > versions? For example what are plans to support live migration from > 4.2 --> 4.3. ? And also how about supporting from 4.3 ---> 4.2 and so > on.This is answered somewhat in http://wiki.xen.org/wiki/Xen_Version_Compatibility The gist is that Xen only in general supports migration between versions within a given stable branch or to (but not from) the next stable version. The primary use case for cross-version migration is to support "rolling" upgrades of host infrastructure e.g. to allow you to update the hosts one by one by evacuating and upgrading each of them in turn. It is not the intention to support host infrastructure containing mixed versions of Xen in the general case. So Migration from 4.2 to 4.3 will be supported, however you should not expect migration from 4.3 to 4.2 to work except by coincidence. Ian.
Hi Ian, Thanks for the reply. How about the use case of "rolling" downgrade? Let us say something is wrong with newer version with infrastructure in my environment and I want to go back to previous version and don''t want to bring my application down. Don''t you see such cases arising? Thanks Siva On Fri, Apr 19, 2013 at 3:30 PM, Ian Campbell <Ian.Campbell@citrix.com>wrote:> On Thu, 2013-04-18 at 16:41 +0100, Siva Palagummi wrote: > > Hi, > > > > > > I am trying to do live migration from Xen 4.1 to 4.2 which is working. > > But not the other way around. Somewhere in mailing lists I read 4.2 > > -> 4.1 migration is not supported. So my question is what kind of live > > migration support that xen team is seeing for the future across > > versions? For example what are plans to support live migration from > > 4.2 --> 4.3. ? And also how about supporting from 4.3 ---> 4.2 and so > > on. > > This is answered somewhat in > http://wiki.xen.org/wiki/Xen_Version_Compatibility > > The gist is that Xen only in general supports migration between versions > within a given stable branch or to (but not from) the next stable > version. > > The primary use case for cross-version migration is to support "rolling" > upgrades of host infrastructure e.g. to allow you to update the hosts > one by one by evacuating and upgrading each of them in turn. It is not > the intention to support host infrastructure containing mixed versions > of Xen in the general case. > > So Migration from 4.2 to 4.3 will be supported, however you should not > expect migration from 4.3 to 4.2 to work except by coincidence. > > Ian. > > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
On Fri, 2013-04-19 at 20:53 +0100, Siva Palagummi wrote:> Thanks for the reply. How about the use case of "rolling" downgrade? > Let us say something is wrong with newer version with infrastructure > in my environment and I want to go back to previous version and don''t > want to bring my application down. Don''t you see such cases arising?It''s not something which I remember being asked for before and its not something that anyone has been putting any effort into. I''m not aware of any of the big consumers of Xen who support this use case. The current support is largely driven by what the users and consumers of Xen have wanted and have them investing the time into making it work reliably and consistently over multiple releases. Obviously downgrading is a bit trickier than upgrading due to the lack of time travel, but if it can be achieved by patches against the N+1 versions of Xen which are not too intrusive I can''t see any fundamental reason for those not to be accepted if someone wants the feature enough to do the work. Ian.