Any backup is only as good as the ability to restore it.
If a ‘backup’ can not be used to restore a system, that ‘backup’ has failed its purpose.
Many different types of backups exist: file system, file cluster, data dump etc, which can be stored on flash drives, hard drives, external Hard Disk Drives or burned to CDROMS or DVDs. It does not matter which type of backup option and storage media is used, if the backup can not be restored, it is useless.
Another problem that occurs can be OS or hardware incompatibility, such as Windows 98 backups not being compatible for restoration on Windows XP computers. Or file systems copied from 32-bit hardware not being compatible for restoration on 64-bit hardware.
Backups can fail for a wide variety of reasons. A verification or monitoring strategy is an important part of a successful backup plan.
From the Wikipedia: http://en.wikipedia.org/wiki/Backup
More sophisticated solutions may exist, but the most basic verification mechanism is to test the backup made.
Imagine a scenario where fancy backup software is in place for a business critical application. Backups are made regularly and even taken off site. Now imagine data loss and the necessity to recover the data contained in that backup. Imagine the disappointment when that recovery fails…
A good backup verification strategy will monitor that
- the ‘correct’ data is in fact included in the backup
- backups match benchmarks
- backups can be restored
This can be broken down into different monitoring actions:
- create a benchmark which contains defined meta data, such as expected file sizes, or number of files, or compression rations and compare the actual backup to the expected values
- create a profile of expected backup content, such as file names, types and sizes and inspect the actual backup content to confirm that the backup content matches the expected content
- set up a ‘restoration test site’ and initiate a simulated data recovery. Establish the time frames and usefulness of the backups available and infrastructure required to achieve recovery in various scenarios, bearing in mind that different backups may serve different purposes
Every backup made can not be tested and verified, but a routine system of checks with scheduled verification should present a clear image of the expected usefulness of backups to different recovery scenarios.
For many businesses, no backup equates to failed business.