Even if you have created the most sophisticated and reliable backup system in the world, your backups can only ever be as good as the data being backed up. If that data is corrupted, then that corruption will flow through the backup system until the original data is lost.
The greatest danger to your data is not catastrophic failure, but subtle damage that goes undetected. The corruption of several files on your disk may cause great damage to your business in the long term, but go entirely unnoticed in the short term. If it does go undetected, the corrupt files will flow through your backups until there are no uncorrupted copies left. This is a particular danger if you don't store a long history of backup. The loss of the disk is a far less threatening disaster because it is immediately detectable.
Thus, it is important not only to backup your data, but to monitor its integrity. This can be achieved using the Veracity data integrity tool from Rocksoft. To use Veracity to monitor a disk, go to the top of the directory tree on the disk to be monitored, and give the command veracity snapshot.
Later, to see what changes have occurred in the directory tree, give the commands:
veracity snapshot veracity signoff
In response to this, Veracity will create a new snapshot and write out a list of changes that have occurred since the previous snapshot. You are then free to investigate the changes and restore any damaged files as you see fit.
By keeping track of the changes on your disk, you can ensure that the data being backed up is sound.
Copyright © Ross Williams 1997. All rights reserved.