I found out by reading some Jira posts, people still use "vzmigrate" to migrate VE from vz7 to vz7 host even "prlctl migrate" should be able to do this. So I installed vzmigrate. At first I got this error:
# vzmigrate -r yes srv01 2f64cf14-2534-4d29-bc71-6046ecfce652
Connection to destination node (srv01) is successfully established
Moving/copying CT 2f64cf14-2534-4d29-bc71-6046ecfce652 -> CT 2f64cf14-2534-4d29-bc71-6046ecfce652, [], [] ...
locking 2f64cf14-2534-4d29-bc71-6046ecfce652
Checking bindmounts
Check cluster ID
Checking keep dir for private area copy
Checking technologies
Check target CT name: VE02
rsync : rsync: --fdin: unknown option
rsync : rsync error: syntax or usage error (code 1) at main.c(1435) [client=3.0.9]
rsync exited with code 1
Can't move/copy CT 2f64cf14-2534-4d29-bc71-6046ecfce652 -> CT 2f64cf14-2534-4d29-bc71-6046ecfce652, [], [] : rsync exited with code 1
But after reading https://bugs.openvz.org/browse/OVZ-6308 I upgraded my systems to VZ Linux 7.3 and all the related latest packages (including rsync which was mentioned in the ticket). So afterwards a migration was working successfully:
# vzmigrate -r yes srv01 2f64cf14-2534-4d29-bc71-6046ecfce652
Connection to destination node (srv01) is successfully established
Moving/copying CT 2f64cf14-2534-4d29-bc71-6046ecfce652 -> CT 2f64cf14-2534-4d29-bc71-6046ecfce652, [], [] ...
locking 2f64cf14-2534-4d29-bc71-6046ecfce652
Checking bindmounts
Check cluster ID
Checking keep dir for private area copy
Checking technologies
Check target CT name: VE02
Checking RATE parameters in config
Checking ploop format 2
copy CT private /vz/private/2f64cf14-2534-4d29-bc71-6046ecfce652
Successfully completed
I hope this post might help someone.