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[Xen-users] domU loses network after a while

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] domU loses network after a while
From: Nathan Friess <nathan@xxxxxxxxx>
Date: Sun, 14 Nov 2010 23:00:16 -0700
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I have a host running Debian Squeeze with Xen 4.0.1 installed from the Debian repository. My host is working fine running 10 domUs, except that after some number of days one or more domUs lose their network interface. In dom0 and domU I'm running kernel 2.6.32-5-xen-amd64 (PV kernel in Debian repo), and interfaces are in a bridged config.

When the network dies eth0 in domU is up as well as vif in dom0, but it seems like no unicast packets make it to/from the domU and dom0. I can run wireshark on the dom0 on vif and see packets attempt to be sent to the domU, but I don't have wireshark installed in the domU to verify what is actually received.

The only thing that I can see coming from domU in wireshark is ARP broadcasts and replies are attempted to be sent, but domU never receives them (arp command shows 'incomplete'). The only other odd thing I see is that the load average is 17 or 18 in each affected domU, while normal domUs are 0 load average. Nothing helpful in dmesg.

At first I had one domU do this after maybe 30 days uptime. Then another did it about 2 weeks later. Now three of them are doing the same thing 8 days later and all three started at the same time (plus or minus a few minutes?). The only fix seems to be to restart the domU. ifdown/up doesn't seem to help.

Is there any way to figure out why domU never receives unicast packets? Is there any other useful info that I can collect to help track down the cause?



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