By default, /var/lib/xenstored is mounted tmpfs in centos 5 but this doesn't appear to be true for Xen4CentOS. This can cause performance issues as mentioned in https://bugzilla.redhat.com/show_bug.cgi?id=446089 I'm not sure if this should be part of xencommons, but if not, adding a tmpfs mount should probably be documented on the quick start wiki page. Thanks, Sarah