Re: [Xen-users] Frozen xen domU

[Mark Adams <mark@xxxxxxxxxxxxxxxxxx>]

Hi There,

Thanks for your response - please see inline.

On Mon, Jul 12, 2010 at 10:42:24AM +0100, Simon Hobson wrote:
> Mark Adams wrote:
>
>> Debian Lenny amd64, xen 3.2.1
>>
>> For the first time in a couple of years, I had a paravirt VM freeze on
>> me the other day, running at 400% CPU in xm list (4 vcpu). The dom0
>> machine was still operating correctly, but the domU was not accessible
>> (either via ssh or xm console). Other paravirt instances on the same
>> dom0 were also still running correctly. After running xm destroy and
>> recreating the vm, it was accessible again.
>>
>> Nothing in the dom0 or domU logs indicate any errors, just that
>> everything in the domU froze about the same time.
>>
>> Has anyone seen this and could offer a reason why or advise how best I
>> might be able to troubleshoot this? This sounds like it's a problem with
>> something inside the VM rather than Xen, however why couldn't I connect
>> with xm console?
>
> Yes, I get this as well.
>
> stop xend - /etc/init.d/xend stop
> find the process id for xenconsoled - ps axl | grep xenconsoled
> kill it
> start xend - /etc/init.d/xend start

I don't think this is the same issue. I successfully stopped the vm with
xm destroy ID and then started it again with xm create vm.cfg.

>
> The DomU will resume where it was. It's sort of second nature - Nagios 
> reports a virtual server as down, first thing I do is log into Dom0 to 
> check.
>
> See this thread :
> http://lists.xensource.com/archives/html/xen-users/2009-07/msg00326.html

Thanks, In your link it says people can connect to the instances but
that they are using all resources. I couldn't connect with console or
ssh at all until I destroyed and created the machine.

I've got a number of Lenny Xen servers running in this way and haven't
had this issue before. As I understand it 32bit dom0 in lenny is a bit
flakey, but amd64 is ok. This is certainly true from my experience
(until this glitch!)

Cheers,
Mark


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