I rebuild my OVM server for the n-th time this morning. Problem was that it was difficult to have the external disk mounted on the /OVS directory.
I tried to add a shared virtual disk - which I formatted as an ocfs2 disk to the existing disk. I found this excellent posting http://geertdepaep.wordpress.com/2008/06/09/oracle-vm-and-multiple-local-disks/ that described the process and guided me into the correct direction. Although the disk was visible in the repos.py script I was unable to see it in the Oracle VM Manager.

Now I thought that I need to build the server and format the filesystems myself.
Sorry I have no screenshots here as the installer runs on the machine itself.
During the installation the two disks (internal 50 GB and external 1 TB) are shown as /dev/sda and /dev/sdb. In the disk setup utility in the installer choose the option to define a custom layout.

The installer offers a predefined layout, which it would normally apply to the available disks.
I decided to have three filesystems on the internal disk. This will be /, /boot and a swap filesystem. On the external disk I gave away the complete disk and formatted it as an ocfs2 filesystem.
During this I received a lot of errors on the screen, stating that there was an error while setting the type of the filesystem to ocfs2. However I continued - ignoring the errors - and finally ended up with this disk layout:

[root@ovm ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 54G 953M 50G 2% /
/dev/sda1 99M 45M 49M 48% /boot
tmpfs 287M 0 287M 0% /dev/shm
/dev/sdb1 931G 315M 931G 1% /var/ovs/mount/6AD759C5D7064B3A9D14BCFFAFC61FC3
[root@ovm ~]#


so, now the fun can begin, as I finally got to the point where I have my 1 TB disk fully exposed for my Oracle VM server.