Xen devel - Nov 2007 - How to debug XEN, in case where DomU/Dom0 gets unresponsive?

Hi all,

I would like to know how to debug xen.

To give some more informations, I would like to explain why I''d like to
do this.

I''ve compiled xen from source (3.1.x/unstable) and installed it on
Debain etch. Furthermore I''ve installed 2 DomU, one HVM (Win2k3) and
one EFW (Endian Firewall, RH-based 2.6.9-55 kernel).

Both DomU''s are running fine for about 15 minutes. But that differs
from time to time. If something happens (like file transfer or http traffic)
then all DomUs and the Dom0 get unresponsive.

I think the "hang" wouldn''t be xen related, if only the DomUs
would crash and the Dom0 would reachable. But with the described problem the
Dom0 also gets unresponsive. Furthermore the DomUs weren''t crashed,
because the console of EFW/"xm top" details this. Anymore I
can''t see any logs at Dom0 that the bridges went down.

A restart of the Dom0 fixes the problem as it appears again the next time.

So, would there be any way to debug this, I think xen-related, problem?

Greetings.

NicoP.


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> I would like to know how to debug xen.
> To give some more informations, I would like to explain why I''d
like to do
> this. 
> I''ve compiled xen from source (3.1.x/unstable) and installed it on
Debain
> etch. Furthermore I''ve installed 2 DomU, one HVM (Win2k3) and one
EFW
> (Endian Firewall, RH-based 2.6.9-55 kernel). 
> Both DomU''s are running fine for about 15 minutes. But that
differs from
> time to time. If something happens (like file transfer or http traffic)
> then all DomUs and the Dom0 get unresponsive. 
> I think the "hang" wouldn''t be xen related, if only the
DomUs would crash
> and the Dom0 would reachable. But with the described problem the Dom0 also
> gets unresponsive. Furthermore the DomUs weren''t crashed, because
the
> console of EFW/"xm top" details this. Anymore I can''t
see any logs at Dom0
> that the bridges went down. A restart of the Dom0 fixes the problem as it
> appears again the next time. 
> So, would there be any way to debug this, I think xen-related, problem?
Do you have any direct physical access to the machine?  Or maybe a remotely 
accessible serial line?  That would make fact-finding easier if (for 
instance) the dom0 network connection has died for some reason but the system 
is actually still up.

Otherwise, I guess you could check the Xend logs for anything suspicious and 
the system logs for any kernel oopses?

From my reading of the code for xenconsoled you should be able to 
run "xenconsoled -l hv" in order to get it to log messages that come
out
of "xm dmesg" into /var/log/xen/hypervisor.log which you could also
inspect
after any crash...  I can''t find a more friendly way of activating that
logging.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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