Disaster Recovery
Even the most fault-tolerant networks will fail, which is an unfortunate fact. When those costly and carefully implemented fault-tolerant strategies do fail, you are left with disaster recovery.
Disaster recovery can take on many forms. In addition to real disaster, fire, flood, theft, and the like, many other potential business disruptions can fall under the banner of disaster recovery. For example, the failure of the electrical supply to your city block might interrupt the business function. Such an event, although not a disaster per se, might invoke the disaster recovery methods.
The cornerstone of every disaster recovery strategy is the preservation and recoverability of data. When talking about preservation and recoverability, we are talking about backups. When we are talking about backups, we are likely talking about tape backups. Implementing a regular backup schedule can save you a lot of grief when fault tolerance fails or when you need to recover a file that has been accidentally deleted. When it comes time to design a backup schedule, there are three key types of backups that are usedfull, differential, and incremental.