Need advice on backup hardware

Question

I am using an Xserve for a disk-to-disk backup, and as our data has expanded, we need more backup room. The Xserve is connected to a RAID, and we need to back up about 1.5 TB from that RAID once a week for offsite storage.
Each night, the backups go to the RAID. All is well there. But the weekly offsite storage is the issue.
This will be rotated weekly, so there would be two offsite drives or modules -- one offsite at all times.
Up to now, we have been using Firewire connected drives, and rotating them offsite has worked OK. Now we are evaluating three ideas to accomplish this task on a more professional level, and I would welcome feedback on these ideas. Tape is not an option.
Options proposed are:
1. Using "raw" drives (1.5 or 2 TB mechanisms) in a simple hard-drive docking station. The drives would be placed in these each week, then stored in a case of some sort when offsite.
2. Using standard desktop drive/case units (i.e. LaCie, Iomega, etc.).
3. Using a rack-mounted solution (OWC, Sonnet, etc) that has FireWire/eSATA connectivity and hot-swap drives in sleds. These, too, would be in a case of sorts when offsite.
4. Using a drive module on the Xserve -- buy, say, two 80GB ADMs and the replace the mechanisms with a 1.5 or 2 TB mechanisms. These, too, would be in a case of sorts when offsite. Since the Xserve is connected to a RAID, one other drive would be the boot/backup software drive and remain in place at all times.
My initial thoughts:
Option 1 leaves the drive too vulnerable, and the units allow the drives to get hot when used for long periods of time. Drives also are spinning down as they are removed, which could be risky. I don't like this idea.
Option 2 works (and has worked) but it involves unplugging FW800 and power cables from the drives, and then these heavy units must be dealt with. An OK solution, but not ideal.
Option 3 appeals to me because it offers some security for the drive (sleds, ability for the drive to spin down once unmounted and before transport) yet without the bulk of an external drive such as a LaCie. Also, being rack mounted, no power or data cables must be touched.
Option 4 is, like Option 3, simple (no power/data to deal with), and offers some security for the drives. But it involves placing unapproved drives into the Xserve as well as putting lots of insertion/removal cycles on the Xserve drive bays (which may or may not be designed for this use).
Any thoughts? I'd really like to get some feedback...
Thanks,
Pete

Answer 1

To clarify:
The data we'd take off site would be a duplicate of what's on the RAID. So in this scenario, nightly backups are done to the RAID, which keeps a week's worth of snapshots. Then, on Sunday, the RAID's content is simply duplicated to an individual drive -- let's say 'Drive A' -- which is taken off site Monday and swapped with 'Drive B.' The following Sunday, the RAID's content is duplicated to Drive B, and the process repeats itself. These offsite drives could/would/are any of the options suggested.
The purpose of the duplicated data is to provide protection in case of a fire or other disaster.
Because of the amount of data -- and the fact that this company only keeps data for a week or so (there is no need for massive long-term archiving; what is archived is done by a different means) -- tape is a costly solution, and it is slow. Tape was used at one time, but the company has moved away from it. Speed, frankly, was a major problem with tape (we still have a Quantum DLT device that holds up to 600 gb (compressed -- reality was about 350gb) data, but it is not being used at present.)
I agree: Your points are valid about the sleds, and the "options." These are the options on the table, and I'm trying to get feedback on these or different options to propose.
Agreed, too: None of these may be ideal. Maybe we should go back to dumping these weekly offsites to the DLT or another tape unit.
Thank you for the input, and any other ideas would be helpful!
Pete