What a RAID is not - a backup method.
It is meant to be used to meet a requirement that a system needs to able to do.
This could be so that a server can keep running and recover due to a disk(s) failures.
If you have a system that needs a very fast response and/or a volume of request as in a database server.
A large file system that can not be stored across separate disks.
I am not saying that you should or should not do it, but more of a do not do it because everyone else is doing this. When a RAID is running well, it is one of the great things to watch; but when it breaks, you are in a world of hurt. They are easy to setup and difficult to configure properly, they have a wicked split personality. You can go for years and feel life is good until it happens - I ended up throwing a disk drive so hard against a wall that it exploded. Two days later, data is restored onto a newly setup RAID.
Some tips on a good RAID:
- get disks of the same series/type but try and avoid the same batch, you do not want them to fail at the same time.
- buy enough disks to handle any future repairs.
- marginal power supplies are not to be used - do not try run a power supply close to its limit. You can get some weird error when the power is unstable.
- isolate the disks as much as possible from vibrations and load noise, it degrades their performance.
- label everything and document everything. You do not want to pull the wrong drive from a RAID that is in a degraded mode and you do not want to have to relearn how to set up a RAID a year later when you have a problem.
- it needs a UPS. one power glitch can result in having it to recover. That can take better than a day if you have a 700+GB disks.
It is sort of like bungee jumping, a lot of fun until the one day you hit the ground - You never look at it the same after that.
