This is expected behavior to prevent disk corruption, during a host 
communication outage.

Excerpt from [1]:
'The worst-case scenario for HA is the situation where a host is thought to be 
off-line but is actually still writing to the shared storage, because this can 
result in corruption of persistent data. To prevent this situation without 
requiring active power strip controls, XenServer employs hypervisor-level 
fencing. This is a Xen modification which hard-powers off the host at a very 
low-level if it does not hear regularly from a watchdog process running in the 
control domain. Because it is implemented at a very low-level, this also 
protects the storage in the case where the control domain becomes unresponsive 
for some reason.'

[1] 
http://support.citrix.com/servlet/KbServlet/download/21018-102-664364/High%20Availability%20for%20Citrix%20XenServer.pdf

Ahmad

On Nov 25, 2012, at 7:51 AM, "Trevor Francis" 
<[email protected]<mailto:[email protected]>> 
wrote:

We performed an IOZONE test through one of our VMs to benchmark our NFS store. 
It saturated the link, causing the NFS server to stop responding. (according to 
the logs on the hosts)

This caused every one of our hosts (Running XS 6.02) to reboot itself.

Nov 25 09:13:24 compute0 heartbeat: Problem with 
/var/run/sr-mount/6b407ac5-aca7-1ade-de4e-765a728d6f52/hb-365a44b3-8083-4b3e-a748-498f3f9b0017
Nov 25 09:13:24 compute0 kernel: nfs: server 172.16.0.5 not responding, timed 
out
Nov 25 09:15:56 compute0 syslogd 1.4.1: restart.


We are running standard NFS on a linux server. The server reported no errors.

We are running CS4.

Why would this happen?







Trevor Francis
Partner
46 Labs | PeerEdge Cloud Switch (PeCS)
http://www.46labs.com | http://www.peeredge.net
720-214-3643- Voice
[email protected]<mailto:[email protected]>

Solutions Provider for the Telecom Industry

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