Re: Inplace upgrading 4.4.x -> 4.5.0

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-02-09 at 20:09 +1100, Steven Haigh wrote:
> On 9/02/2015 7:59 PM, Sander Eikelenboom wrote:
> > Monday, February 9, 2015, 9:35:33 AM, you wrote:
> > 
> >> Hello Steven,
> >> upgrades from Xen 4.4 to 4.5 are supposed to work out of the box.
> > 
> >> Please post more details and we'll try to help you figure out what's
> >> wrong.
> > 
> >> Cheers,
> > 
> >> Stefano
> > 
> >> On Sun, 8 Feb 2015, Steven Haigh wrote:
> >>> Hi all,
> >>>
> >>> I was under the impression that you should be able to do in-place
> >>> upgrades from Xen 4.4 to 4.5 on a system without losing the ability to
> >>> manage DomUs...
> >>>
> >>> This would support upgrades from running systems from Xen 4.4.x to 4.5.0
> >>> - only requiring a reboot to boot into the 4.5.0 hypervisor.
> >>>
> >>> When I try this in practice, I get a whole heap of permission denied
> >>> errors and lose control of any running DomUs.
> >>>
> >>> Is there some secret sauce that will allow this to work?
> > 
> > You are probably running into a mismatch between the running hypervisor (4.4) and 
> > the now installed toolstack (4.5) .. for instance when trying to shutdown the VM's
> > to do the reboot. 
> > (Since the newly installed hypervisor parts are only loaded and run on the next boot).
> 
> Correct - It is the 4.4 Hypervisor with 4.5 toolstack. After a reboot,
> all is good. However this causes the problem - once you update the
> packages from 4.4 -> 4.5, you lose the ability to manage any running DomUs.

This sounds like a packaging issue -- Debian's packages for example jump
through some hoops to make sure multiple tools packages can be installed
in parallel and the correct ones selected for the currently running
hypervisor.

Otherwise I think the upgrade path is:
      * shutdown all VMs (or migrate them away)
      * install new Xen + tools
      * reboot
      * restart domains with new tools.

I'm afraid that using old tools on a new Xen is not something which is
supported, even in the midst of an upgrade and AFAIK never has been. The
N->N+1->N+2 statement is normally with reference to live migration (i.e.
you can live migrate from a 4.4 system to a 4.5 one).

Ian.