[Pkg-xen-devel] Re: [Pkg-xen-changes] r55 - trunk/debian [u]

[Ralph Passgang]

Am Samstag, 25. Februar 2006 14:38 schrieb Guido Trotter:
> On Sat, Feb 25, 2006 at 01:54:13PM +0100, Ralph Passgang wrote:
>
> Hi,
>
> > > Then we need for the new package to have a "Replaces:" on the first
> > > one...
> >
> > yes, probablly that fixes that, but I cannot test an upgrade anymore. I
> > don't have xen2 machines anymore...
>
> Do you remember which packages cause that error, so we can do it properly?

no, but if it's really important I could drive tomorrow to work, because I 
would have enough free pc's there to test it again.

I am also not sure if "Replaces:" helps a lot, but we can test that too then.

But for today I have not enough time to drive to work and test, sorry. But 
Julien also wanted to test that today if I got that right.

> > If I am not totally wrong adams packages call "xend stop" and then
> > "xendomains stop". By doing this the domUs will NOT be stopped, because
> > xend was stopped first and xendomains will fail because it cannot contact
> > xend anymore.
>
> I see... Then it's a bug in the older packages... We can probably ignore
> it, and put in the NEWS not to upgrade with VMs running... A fix would be
> to upload a transitory xen 2, but it seems like an overkill!

I don't know if it is a bug or if it was a kind of hook adam used to not stop 
vm's during an upgrade of the xen packages. But it was at least ugly and 
showed a lot of errors (even if dpkg/apt ignored that and continued upgrading 
then).

I checked that again, because I don't want to tell you something not true, so 
here is adams relevant part of the "xen.prerm" file:

...
invoke xend stop
invoke xendomains stop
...

> > This probably means that after a upgrade from 2.0.6 -> our 3.0.1 packages
> > there will still some domUs running, but the user cannot shut the domus
> > down anymore (unless he is not ssh'ing into every domU). the userspace
> > tools will not be able to communicate with a 2.x hypervisor.
>
> Understandable...
>
> > absolutly an overkill. How do you want to keep old files, even if the xen
> > packages gets updated?
>
> Yeah, you're right... :)
>
> > Maybe we should just include a BIG warning before upgrading that it's
> > better not to try a upgrade within a running xen system at all. It's the
> > best to start a normal kernel (and having no domUs running then) and
> > update xen and reboot the new hypervisor + kernel then.
>
> Well... if you have no VMs running it's already ok, I think... there's no
> need to actually boot inside a linux only system! Let's not scare the
> users! ;)

correct, but not having xen run at all is an advantage, because then xend & 
xendomains is not running at all and nothing bad will happen for sure. I am 
not sure what happens if a xen2 hypervisor is running and xend3 is started. 
Will it start but not working? Or will it not start at all and if so, is it 
breaking an upgrade causing dpkg to stop or is it juse something that looks 
ugly but is not really important.

on our production system at work I started the default debian kernel before 
upgrading from my 2.0.7 packages to 3.0.0, because I wasn't sure what will 
happen and I don't wanted to check that on a production system.

so we have to test at least now and depending on what happens we have to find 
a user-friendly solution or even add a "scaring" warning (if really needed). 
it's better than having a user making bad expierence because of broken 
filesystems in his domUs (because when he finally rebooted his domUs weren't 
stopped correctly!).

> Thanks,
>
> Guido
>
>
> _______________________________________________
> Pkg-xen-devel mailing list
> Pkg-xen-devel at lists.alioth.debian.org
> http://lists.alioth.debian.org/mailman/listinfo/pkg-xen-devel