Not knowing what OS/ system you have, in MS Windows Server 2008 Enterprise I run a RAID array with mirroring plus shadowing with nightly offsite backups.
The RAID with mirroring protects against a single hard disc failure. Everything written to one is concurrently written to the other.
The shadowing allows giong back through the last 64 "snapshots" of what was/ is on the disc. This would be helpful, for instance, if you got a virus attack you could "go back" to when you had a stable system.
The nightly offsite backups allow going back through the past 30 days of backups. This can be useful if, for instance, you had a system threat arise but not execute, you could "go back" to a stable time. Also in the event you entire facility/ office/ house/ etc. ceased to exist (fire, etc.) you can restore the entire system to any other system in the world. You are limited though in bandwidth in restoring a system so don't think it's "instant" because it is not. You can do simple math to take your backup set size divided by the datarate (20mpbs on a decent cable modem) to see how long it would take to restore a completely failed system. The downside is the time to restore but the upside is that there is a means to restore.
It all depends on what you have going on.
For simple (and I mean really simple to use) free and/ or cheap offiste backup check out idrive dot com. They have a small free service and cheap bigger services. No hardware necessary and free software from them.
