First, you have a pool of Citrix Xen servers and you want to change the pool master.To control a pool of servers, you would need to connect to the pool master server. Citrix Xen Server populates the management database among all the servers, however only one is the master server.
Go to the slave server that you want to use as pool master.
#xe pool-ha-disableList UUID for all the hosts
#xe host-listEnjoy it ...
# xe pool-designate-new-master host-uuid=
If the pool master is down , use the following commands.
then re-establish connectio to the slaves.
# xe pool-recover-slaves