Re: [Xen-devel] Inplace upgrading 4.4.x -> 4.5.0

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 09/02/2015 09:09, 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 is problematic - if only for the fact that you can't shut down
> running DomUs for the Dom0 reboot.
>
> I understand that large jumps in versions isn't supported - but I
> believe that point versions should be supported using the same toolset.
> ie 4.2 -> 4.3, 4.4 -> 4.5 etc.
>
> I'm just about to gather some data for it - and I'll make a new thread
> with what I can gather.

This is because of the removal of Xend.  In the past, Xend was a daemon
process and would have continued to use the old libraries it loaded when
it started.

With xl and libxl, the new process will fall over an EACCES from Xen
(mismatched tools and hypervisor) before it can identify the correct
daemonised libxl process to talk to to shut the VMs down.

~Andrew


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