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Re: [Xen-users] domU loses network after a while

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] domU loses network after a while
From: Nathan Friess <nathan@xxxxxxxxx>
Date: Thu, 18 Nov 2010 10:55:11 -0700
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Nathan Friess wrote:
Hi,

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.


In case anyone runs into something similar, I did figure out how to resolve my issue without having to reboot the domU... which is a slight improvement I suppose.

Running
   xm network-detach domUName 0

Causes eth0 to disappear in the domain, and the following to show up in dmesg:

  net eth0: xennet_release_rx_bufs: fix me for copying receiver.

Then running an xm network-attach will bring eth0 back and everything will be okay.

I also tried rmmoding xen_netfront in domU before I figured out the network-detach, but this doesn't help. When modprobing again, the domU says "eth0: link is not ready". This also causes any subsequent attempt to network-detach in dom0 to get stuck and eventually timeout with "Device 0 (vif) could not be disconnected."

Also, when the vif is stuck, the TX dropped packets shown in dom0 is steadily increasing. It seems that dom0 is having trouble sending packets to domU because one of the two gets stuck in an unexpected state. At least doing a network-detach will reset the state and allow things to run properly again.

Nathan

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