A RHEL3 machine (containing this RAID) won't get changed physically, but the workstation will be wiped out by reloading it with RHEL4. Planning question: Although RAID disks won't be touched by the reload(different disk for boot device, etc), will the RAID have to be recreated then data restored under RHEL4. Do I just have to migrate this file?

Prior to system reload, everthing will be fully backed up as a precaution.

# cat /etc/raidtab
raiddev /dev/md0
raid-level 0
nr-raid-disks 4
persistent-superblock 1
chunk-size 64
#
# when formatting, use the following rules
# for ext3, use -R stride=chunk-size/block-size
# so, for 64k chunk-size and 4k block, stride=16
# mke2fs -j -b 4096 -R stride=16 /dev/md0
#
#
device /dev/sdb1
raid-disk 0
#
device /dev/sdc1
raid-disk 1
#
device /dev/sdd1
raid-disk 2
#
device /dev/sde1
raid-disk 3
#
Thanks in advance...

Assuming it's mdadm with normal superblocks and your raid is healthy, there's no reason that you'd need to recreate it.

Similarly, if you have your raidtab, you should be able to drop it in and mdadm should just kinda magically see the raid and assemble it.

If it doesn't (ie: if the different kernel version labels the disks differently for some inexplicable reason or something bad happens), you should probably familiarize yourself with the "assemble" mode of mdadm by reading mdadm's man page.