Howto: Changing iso image in Xen

1. xm block-list "name of the domain"
Vdev BE handle state evt-ch ring-ref BE-path
768 0 0 1 -1 -1 /local/domain/0/backend/vbd/1/768
5632 0 0 1 -1 -1 /local/domain/0/backend/vbd/1/5632
2. sudo xenstore-write /local/domain/0/backend/vbd/1/5632/params /path/to/your/iso/file

3. Done