Accusys SCSI & RAID Devices Driver

There are several vendors on the market - Accusys comes to mind as one - that offer RAID controllers which emulate single drives. You install the RAID box in a 5.25' bay, connect your drives to the RAID box, and then connect the RAID box to the SCSI controller. If your goal is RAID 1, then it meets all your needs: no drivers to worry about and any single drive may be removed and connected directly to a SCSI controller to retrieve the data. For RAID 5, I believe that if replacement hardware is unavailable you would be in trouble no matter what hardware solution you choose. The only way to cover your back 99.9% would be to purchase spare RAID hardware just in case your setup fails and the vendor disappears.
Of course, you aren't using the RAID as a backup solution, right? It isn't a backup solution, it is a redundancy solution. A backup solution is something you can take off-site in case the building burns down, or floods, or gets picked up by a tornado, or the building is broken into and the disks are stolen, or... well, you should get the picture by now. A redundancy solution only provides additional insurance against downtime.
They have a number of products at their website (www.accusys.com.tw) that you may want to look into. I've heard only good things about the ACS-7500. Granted, it's not SCSI, but it is an indicator that their SCSI stuff is probably good as well.
Accusys SCSI & RAID Devices driverDriverAccusys SCSI & RAID Devices DriverDriver

Accusys Scsi & Raid Devices Driver Updater

SCSI/RAID Controller: ACARD AEC67160 PCI Ultra160 LVD/SE SCSI Adapter: Acard: SCSI/RAID Controller: ACARD RAID PROCESSOR: Acard: SCSI/RAID Controller: ACS-6xxxx: Accusys Inc. SCSI/RAID Controller: ActiveImage Protector Virtual Storage Adapter: NetJapan: SCSI/RAID Controller: Adaptec 2000S Ultra3: Adaptec I2O RAID Adapters for Windows 2000 & XP. Accusys A16T3-Share External Thunderbolt 16-Bay RAID System. Accusys A16S3-PS ExaSAN 16-Bay Rackmount RAID Storage. Accusys A12T3-Share+ 12.