I've just had a controller failure in a dual controller SATA disk array.
The redundant second controller is still functioning and all of the
disks are available. However, the server,a RHEL3 update 5, system,
can't mount 2 of the 4 luns because it can't use the original device
paths, /dev/sdg1 and /dev/sdh1.

What do I need to do to be able to remount the luns?

The following process worked for me:
While the server was still up and running, I unmounted the 2 remaining luns.
I then modified the fstab so that none of the luns would mount at boot, and
disabled the service which would use the luns at boot.
Then I rebooted both controllers in the disk array and was fortunate enough to
have both controllers come back up.

I then rebooted the server and was able to fsck all 4 luns, after which I was able
to mount all 4 luns, start up the disabled service, and put the server back into full
service.