Here is how I did when doing fully virtualized 1. First find out where the iso is mounted : a. Xm block-list domain-name This should return something similar to following: Vdev BE Handle state evt-ch ring-ref BE-path 768 0 0 1 -1 -2 /local/domain/0/backend/vbd/8/768 5632 0 0 1 -1 -1 /local/domain/0/backend/vbd/8/5632 2. Now after finding that out do the following: Xenstore-read /local/domain/0/backend/vbd/8/5632/params This should return: /root/rhel-5-server-i386-disc1.iso or wherever your isos are stored 3. Now can do the following to change which iso should be read: Xenstore-read /local/domain/0/backend/vbd/8/5632/params /root/rhel-5-server-i386-disc2.iso