Classifying data for disaster recovery
Because disaster recovery planning usually starts with a budget, and because making a disaster recovery budget usually starts with dividing data into classes, you need a classification scheme early on in the process.
CNT suggests that data can be classified according to Recovery Time Objectives (RTO) i.e., how soon after a disaster the lack of the data will begin to have a severe impact on the enterprise's operation. For example, CNT suggests, the most critical data class might have a severe impact on the business within 8 hours, the next most critical class might have a major impact after 72 hours, and so on. Using time to restore as a metric not only provides the necessary classification, it also automatically sets deadlines for planning the recovery.
In using a time-based classification scheme, CNT points out that it is important to realize that there are multiple factors in the recovery process, including everything from time to get the data to the disaster recovery site to the time to restore connectivity as well as the time to actually restore the data. All these elements need to be included in the disaster recovery schedule.
CNT discusses this concept as well as other aspects of data recovery in a white paper titles "Classes of Recovery", which is available on the CNT web site.
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.