Apple Xsan (upgrading to Xsan 1.4) - Manual (Page 17)

Chapter 2 Upgrading to Xsan 1.4 on Mac OS X version 10.4 17
Step 6: Optionally, return control of volumes to a specific controller
When you restart a controller during the upgrade process, control of the volumes
the controller is hosting switches to a standby controller. After you finish upgrading,
you can use the
cvadmin
command-line tool to return control of a volume to a specific
controller.
To switch control of a volume to the other controller:
m Go to a controller, open Terminal, and type:
$ sudo cvadmin -e ”fail volume“
where volume is the name of the Xsan volume.
To see which controller is hosting a volume:
m Open Xsan Admin, select the volume in the SAN Components list, and click Overview.
The name of the volume’s controller is to the right of “Hosted by.” You can also find out
which controller is hosting a volume using the
cvadmin
tool in Terminal. Open Terminal
on a controller and type:
$ sudo cvadmin -e select
If you have more than two controllers:
You can’t directly specify the controller that a volume switches to during failover.
Xsan chooses a standby controller based on its failover priority and other factors.
If you have only two controllers, you know the volume will switch from one to the
other, but if you have three or more controllers it can be more difficult to know which
standby controller will assume control. To be sure that a volume switches to a specific
controller, you can temporarily change the role of the third or any additional controllers
to Client during the failover.