Separation is Critical to Your Backup Strategy
A Backup Article Contributed by Daniel Jones
Thinking about Backup during a Recovery
For some reason, most people don't seriously consider forming a backup strategy until they have experienced a significant data loss. A this point they are willing to consider all sorts of methods to protect them from data loss, but are quite put out that the new backup strategy will not help them recover what has been lost.
Failed Backup, a Double Disaster
The only thing worse then having to restore to your backup after a data loss is finding out that your backup has failed as well. This is why most experts advise your backup strategy include multiple backups and backup methods with a degree of separation between them. Without well separated and multiple backups you will often find the same issue that took down your live data will effect your backup as well.
Three Types of Backup Separation
In order to limit the number of single points of failure that can take down all your backups, it is important to separate your backup strategies in three ways. First and most obvious is the location of your backup media storage. Having a the library of backup data tapes in your server room may be convenient, but it does you little good when the fire that destroys the original also destroys your library. As many people find to their dismay, fireproof safes are often not. At a very minimum you should store copies of your backup tapes offsite and update the offsite backups regularly.
The second type of separation is method. In our previous example, storing copies of your tape backup offsite is a good first step, but if your tape backup software or hardware fails you would still be left with multiple copies of a failed backup. A more secure alternative would be to mix they backup methods, for example a local copy of your tape backups, with an offsite online backup.
With this strategy, even if the online, or tape backup were to fail due to problems with the internet connection, or other software/hardware issues, their is an excellent chance that the other backup will still be available.
The third and final type of separation we will discuss is that of time. A common problem with failed backups is that when the backup is taking place, one of the files that needs to be backed up is locked, or in use. The ideal cure for this is to monitor your logs and reports and schedule the backup to occur at a time when the task locking the file is not running. In the real world however, this is not always possible.
Since we discussed the importance for multiple backups in the previous paragraph, just make sure that their is a significant difference in time between the two backups. This gives us a better chance that one of the two backups will pick up the problem file. Despite this you still need to pay close and daily attention to your logs and reports.
