RAID or not...

for working? or just for storage?

 

If you are thinking of using 2 drives, with 2 as backups, I would vote for 4 separate drives (no RAID). Keep them in separate places (preferably 1 set off site). Update the offsite set weekly or after a big job, update the main set after any major work is done.

This is logistically a little complicated, but provides a lot of data protection. If you used RAID 1 drives, a single power fault could easily take out both. With separate drives, they are only both powered on once a week or so for a few hours.

If it becomes too complicated to manage all of the separate external drives, something like a Drobo or NAS works well, but costs a lot more and can be taken out by a single surge. It also needs fewer drives for the same storage capacity (my way needs 2*n drives where n is the storage capacity I require, most NAS/Drobo require n+1 drives to have redundancy).

Currently I am running 2x2.5, 4x3.5 and a time capsule for my backups and it is starting to become annoying, but is still less than half the price of a network storage solution.