An Ubuntu LTS server runs xen with dom0 and one virtual machine. The server is freezing permanently on a number of seemingly unrelated operations, such as:

  • Creation of a new file system with mkfs.ext3 on a LVM device. (this is consistent).
  • Restart of xend via /etc/init.d/xend restart
  • apt-get dist-upgrade on configuration phase of some fairly innocent stuff.

Also, yesterday I noticed that virtualized imagine had lost time synch and complained about backwards clock in dmesg.

Unfortunately, I don't have the screen shots on what happens actually on the console of the server (it is co-located).

I want to blame ram, but do You have other suggestions?

UPDATE: After further investigation, it appears that all those actions only kill network. When I visited the server in data center and logged onto console, I wasn't able to reach my router/gateway. How bizare.

  • Is there any useful information in dmesg? – Ophidian Jan 3 '10 at 20:30

for the network issue, xen works better if you don't let it set up the bridge...

for /etc/network/interfaces

auto xen-br0
iface xen-br0 inet static
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0


(vif-script vif-bridge bridge=xen-br0)

this way starting and stopping xen won't mess with your network interface.

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Yeah, I'd be running a lengthy memtest first up, but there's a decent possibility it's something else hardwareish -- run a complete burnin of all system components, and monitor all your temperatures.

The clock thing is unrelated, Xen just can't keep good time. NTP forever.

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That does look like hardware failure. Test the ram and also check the hdd for bad sectors. Also check the log files for any warnings.

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  • Logs are always clean :( – Konrads Nov 3 '09 at 9:42
  • And the system completely freezes? I still recommend checking for bad ram and bad hdd sectors. If it's possible, run something like Prime95. When it's a CPU or RAM problem, it will show. Also, what are the temps? – The_cobra666 Nov 3 '09 at 10:01

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