I am trying to set up a test cluster on a Xen Server with 2 paravirtualized CentOS 5.4 machines. I am using Pacemaker+Corosync, and following the instructions found at http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf and other sites. Anyway, when I try to manually stop the corosync service, about 80% of the times the whole VM locks up with the message "Waiting for corosync services to unload" and I am forced to shut the machine down manually. For the remaining 20%, the VM keeps responding and adds dots to the above message, but it won't actually stop the service. There aren't many resources on the internet about this particular error. Any ideas about this? Thanks in advance.