Re: [Xen-devel] Question about xen network and strange happenings with migrating a node

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-02-08 at 19:44 +0000, Kris wrote:
> Hi,
> 
> I've been experiencing some issues with Xen-3.4.2-2.el5 (from gitco)
> on CentOS 5.4 when migrating nodes from one physical node to another.
> Each VM has 3 network interfaces (vifs).
> 
> When doing a live migration (xm migrate --live <params>) the network
> of the migrated VM seems to go in to a very odd state when it's done
> migrating. I've searched high and low for some documentation on what
> the state, evt-ch,tx-/rx-ring-ref fields mean with their particular
> integer values, but 1,-1,-1/-1 respectively seems to be indicative of
> something that has gone badly. A state of 4 seems to indicate that the
> interface is in a working state.
> 
> When doing a xm network-list VM on the node it is being migrated *to*
> - in this case all of them are broken, but sometimes it's just one or
> two interfaces are in this state.:
> Idx BE     MAC Addr.     handle state evt-ch tx-/rx-ring-ref BE-path
> 0   0  <REDACTED>   0     1      -1    -1   /-1      
> /local/domain/0/backend/vif/2/0  
> 1   0  <REDACTED>    1     1      -1    -1   /-1      
> /local/domain/0/backend/vif/2/1  
> 2   0  <REDACTED>    2     1      -1    -1   /-1      
> /local/domain/0/backend/vif/2/2
> 
> The result is that the network interfaces with the output above do not
> work.
> 
> Is there anything I can do to perhaps debug this better? Is there any
> documentation I'm missing out that would explain this stuff? Any
> troubleshooting help is appreciated. I've looked at the xend logs and
> there doesn't seem to be anything indicative of why this is occurring.

There's a good chance this is a guest kernel issue. What sort of guests
are they and what kernel version are they running? Is there anything in
the guest kernel logs or on the guest console?

The output of "xenstore-ls -fp" after this has happened would also be
potentially interesting.

Ian.



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