For those of you who want to see what performance is like within your XenServer environment, this VM provided by Citrix will give you a little more insight into your Xen infrastructure.  You can download the .xva here.

Preparing iSCSI LUN for testing

Accessing the Web interface for disk performance

From Citrix Support:

When a new host joins an existing pool of XenServers and network names have been changed manually, the pool's network configuration does not merge correctly. As a consequence, live migrations of Virtual Machines (VMs) are not possible. This is due to an inheritance problem in the pool configuration. This hotfix resolves this issue.

We have encountered this issue, and the hotfix did the trick for us, just wanted to pass along in case anyone else is having this problem.

We are in the process of moving our Xen Server VM's over from an AMD based host to an Intel based pool.  On some of the servers we have had to re-activate Windows and other we haven't.  I would think that all of the VM's would need to be re-activated due to the hardware changes on the Xen host.  We haven't had any problems other than re-activating the servers after they have been moved.  On the AMD Xen Host we exported the VM's as a backup and on the Intel based Xen Pool we imported them to the SAN.  I've read quite a bit about this in the Citrix support forums and the jury is still out whe