Incremental Backups

A "normal" incremental backup will only back up files that have been changed since the last backup of any type. This provides the quickest means of backup, since it only makes copies of files that have not yet been backed up.

Wikipedia

• It's quick: There are only so many files that have changed since the last backup.
• It's cheaper: You don't need as many backup media because there are only so many files that have changed since the last backup.

It must be a win, win: cheaper, faster what's not to like?

Problems with incremental backups

In theory, it's great, in the real world, you will fall flat on your face if you use incremental backups. If the hard drive crashes:

1. You go to the store and buy a brand new one, usually a larger one because the smaller ones are not available anymore, and there is more storage space.
2. You install the new drive.
   1. You can't start the recovery, you need to install the backup software.
   2. You can't install the backup software, it only runs with either Windows or OSX.
3. You need to install the operating system, either windows or Apple OSX.
4. You need to install the backup/recovery software.
5. Wait, you still need to find the last full backup done.
   1. No, it's not that one.
   2. No, it's still not that one, You did put it aside and clearly labeled it as do not touch! or did you overwrite it?
   3. If you did overwrite it, that's it, you are finished, no valid backup: everything is lost.
6. Finally, you found the last full backup, restore it.
7. Now, you still need to restore all the incremental backups in the correct orders. You labeled the drives properly? Didn't you?

Got all these steps right and in the correct order? Too often, I have seen it fail. In computer jargon: it's too many point of failures.