Re: [Xen-users] Weird issue on heavy server

[Andrew Pitman <andrewpitman@xxxxxxxxxxx>]

Alexandre,

I think I've run into this as well, on 4.1.2.  As far as I could tell, it was 
an issue with the bridged ethernet shared by my dom-Us (at the time, all hvm).  
Each domain had its own MAC address.  The domains could still communicate 
amongst themselves internally on the Xen server, but nothing was being 
forwarded between the bridge and the physical network.  A "service network 
restart" on my Fedora 13 dom-0 (2.6.32.40 kernel) fixed the problem, but I 
still have no idea why it did that in the first place.

I speculate that it might have had something to do with the allocation of 
vif/tap devices and the fact that they don't seem to be properly recycled when 
enough VMs are shut down and restarted on the system.  Or at least, they always 
seem to increment as far as I can remember.

Andy
--
Sent from my iPhone appendage

On Aug 27, 2012, at 11:48, Alexandre Kouznetsov <alk@xxxxxxxxxx> wrote:

> El 27/08/12 04:53, DN Singh escribiÃ:
>> The problem that we are facing on two of them is, network on some VMs
>> gets stuck.
>> We cannot ping or SSH the VMs from outside the network, but xm console
>> shows the VMs are fine. The only confusion is why only on 2 VMs, and
>> that too on 2 nodes?
> Local firewall? iptables -L -v shall answer.
> 
> Are they PV or HVM?
> 
> What about "inside network"? Can a VM (controlled via console) do ping or 
> whatever? Does it behaves differently while communicating with outside world 
> and other VM on the same host?
> 
>> Can someone please direct me in the right direction? Also, please let me
>> know if more information is required.
> Check with tcpdump, if you see traffic on your bridge while tying to 
> communicates with VM's.
> 
> -- 
> Alexandre Kouznetsov
> 
> 
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