While it's a bit dated, this book, Backup & Recovery: Inexpensive Backup Solutions for Open Systems (http://www.amazon.com/Backup-Recovery-Inexpensive-Solutions-...) is highly recommended. And higher level programs like BackupPC and Bacula are still excellent solutions.

It's comprehensive, covers off-line bare metal backups (which aren't exactly changing any time soon), points you at tools like rdiff-backup which you can use to get reasonably close to continuous data protection (I do it every hour), etc. etc. Along with a few good and short war stories. And preps you for the big times, if you're interested.

I divide my backups into three types:

  Bare metal.

  Frequently changing data.

  Occasionally changing data.

Everything is weighted by how automated I can make it (e.g. everything but some day to day monitoring), what worse case recoveries are possible (no one cares about backups, only recovery) and time to recovery (my personal use, so a few hours are OK). And the threat level, e.g. a fire in one room (sprinklers) and the possibility a tornado would take out the local hardware but leave me alive (I live adjacent to tornado alley and have lived through a couple).

So I have a bare metal backup of a compressed image of my system drive (made with dd using a live-CD) which is updated every time I mess with LVM and nightly snapshots of my root partition (LVM snapshop of partition with dd).

From that toe-hold I can rebuild my system from any worse case short of hardware destruction, I use nightly backups with BackupPC for normal system recovery, augmented with what's below for frequently changed data.

Frequently changing data, like email and code I'm working on, is rdiff-backup snapshotted every hour. If I was maintaining customer data I'd do a continuous process.

The same data is rsyncsrypto-ed and most of that is rynced to rsync.net.

Occasionally changing data is rsynced every night.

I try to avoid common mode failures, e.g. no one piece of software, one system or one disk will cause total data loss.

Ask if you want particular details; for a long treatment of this, read Backup & Recovery, "Inexpensive Backup Solutions for Open Systems" by W. Curtis Preston (http://www.amazon.com/Backup-Recovery-Inexpensive-Solutions-...). It's getting to be a bit old, but a lot of it still holds and the principles will be true for a long time.

(Note, while the above particularly paranoid approach is for my personal systems, it's based on harsh experience going back to 1977 (sic), including plenty of small scale "enterprise" systems where total data loss was unacceptable and a couple of 24x7 Internet startups.)