I'm not really conversant in RAC, or ocfs2, but I think what you are looking at is at a lower level that that.
On Red Hat 4.5 you have DM-Multipath and LVM2, both of which I'm familiar with and we use heavily at my company.
This is a little wordy, so bear with me.
If you do an 'lsscsi', you should see all of your scsi block devices, i.e. /dev/sdaj and /dev/sdak. It won't tell you very much about them though, just that they have been recognized and are there.
If you are running DM-multipath (we do on our RAC systems) the underlying SAN scsi devices are "matched up" (by reading the serial number from each device) and are represented by an 'mpath' device, e.g. /dev/mapper/mpath2.
If you do a 'multipath -ll', you should see those underlying devices mapped to 'mpath' devices.
(There is also the dmsetup command, 'dmsetup ls', that shows the multipath devices (lvm, dm-crypt, dm-multipath, ...) whatever you are using.)
The ext2/3/4 LABEL or the UUID of a device can be used to mount it and eleviates the problem where you mount an explicit device name and the names have "shuffled" on you.
With LVM you have metadata written to the various "volumes" of LVM. When you do a 'pvcreate' on a partition (or full volume), metadata is written to that partition (or full volume); then when you do a 'vgcreate' or 'vgextend', more metatdata is written there; same with 'lvcreate' or 'lvextend'. When LVM is initialized as the system comes up, it scans for that metatdata, again alleviating a dependence on explicit device names.
On a "normal" non-RAC system, the mpath devices can be formatted (preferably with an ext2/3/4 LABEL so you don't have to worry about device names changing) and mounted (I think). A better practice is to use LVM.
With ocfs2 you don't use LVM or mount the devices directly. It does (at least in my shop) use the multipath device (e.g. /dev/mapper/mpath2) but mounts what look like partitions (e.g. /dev/mapper/mpath2p8 on /u08 and /dev/mapper/mpath2p9 on /u19).
Do a 'mount' command to see what you have mounted now.
Sorry I can't tell you much more than that. If you are using ocsf2, you can post another question that is ocfs2 specific and you should find someone that is more authoritative than me.
btw, RHEL4.5 is very old and was pretty buggy. We tried it and then went to RHEL4.6 + a higher level kernel. When Oracle finally supported RHEL5, we went to RHEL5.2 and then RHEL5.4.