Backup multiple drives to a single drive

[claude-h]

I have another question about my backup strategy from above but isn't really SuperDuper! related, but I thought maybe you could give me your advice.

The backup drive I ordered is an IOMEGA UltraMax 640GB, which contains two 320GB drives, that can be set up either as a simple volume (Non-RAID), as a Spanned Volume (JBOD) or as a Striped Volume (RAID 0).

The capacity of my 3 drives I want to backup is as follows (real capacity in brackets):
1. iMac's internal HD: 80GB (74.4GB)
2. LaCie external FW HD: 250GB (232.7GB)
3. LaCie external FW HD: 250GB (232.7GB)

I don't know yet if the two drives in the UltraMax have a real capacity of 320GB or if it is in fact 298GB.

Initially I wanted to use RAID 0, but I guess since I have to partition the drive into 3, that wouldn't make much sense anymore, as I would end up with each partion being spread across the two drives.

I guess a Non-RAID configuration won't do me any good either because I need two 235GB partitions and one 75GB partition. If the two drives in the UltraMax have a real capacity of 320GB than I could use a Non-RAID setup but in the more likely case that the drives in the UltraMax have a real capacity of 298GB, this scenario won't work.

So I would have to use the JBOD configuration in order to achieve the backup strategy I want to use, or is my preferred method (RAID 0) still the way to go?

I'm sorry if I'm not supposed to post threads that don't concern SuperDuper! directly but I thought maybe you could clear this matter up for me.

Again thanks for your great help,

Claude