The Importance of Testing Backup Software
A Backup Article Contributed by Andrew Whitehead
Reasons for Testing Backup Software
How confident are you in your backup software? If you really believe that your entire backup system works, would you be happy reformatting your hard drive right now, and restoring it from backups?
If not, you should be asking yourself why not. Your backup system may be very sophisticated, well planned, and extremely comprehensive, but you will never know if it works unless you actually test it.
Reasons for Backup Software Failing
Your backup software may simply fail, and though you used the 'verify' option you find that when you try to restore from the backup media many files are missing or corrupted.
You could discover that your backups are incomplete, and your reassuring collection of backup tapes are all of one directory because the backup software was wrongly configured.
Encryption may seem like a good idea, until you find that nobody knows what the password is.
You try to reload an old backup tape, and find that it can only be read by an earlier version of that backup software that you recently upgraded.
How good is your media? Have you ever tried to get data off it after six months?
You tested your backups, and everything appears to be working. Then you decide to upgrade your operating system, and find a previously dormant bug in the backup software that causes backups to fail.
It is not unknown for a backup tape to break during backup, and get sent offsite without anyone noticing.
You run a routine backup overnight, and as usual the tape is on your desk next morning - but nobody tells you that they found the machine rebooted. The system had crashed in mid-backup and the tape drive automatically rewound the tape.
These lighthearted examples are to get you thinking about the numerous things that can go wrong with a backup operation. Some of these will be with your backup software, some will be intermittent, others will be system problems, but they all your render your backups useless.
The only way to find these problems in your backups software is to actually perform a trial restore from a backup. For many users, who have completely filled their hard drive, this may be difficult but testing your backup is important. Reduce the clutter on your disk to less than half the capacity or find another hard disk so that you can .
The Ultimate Backup Software Test
Even when you have run a trial restore of a backup, and the data is on your disk, are you sure that the restored data is sound?
Now you need to perform an integrity check, using a data integrity tool such as Veracity. These work by taking a snapshot of the directory tree before making the backup. These snapshots are very small, typically around 1/200th of the size of the tree itself, and get backed up along with the other files in the tree.
When that backup is restored, the integrity tool will read all the files in the restored directory tree on the hard drive, and compare the signatures to those in the snapshot file and warn you if anything changed. The advantage of this is that the snapshot file is part of the backup itself, so this method can be used even for old tapes.
