Page346

Backups and Availability

Although backup techniques are also reviewed as part of the “Fault Tolerance” section discussed previously in this chapter, discussions of Business Continuity and Disaster Recovery Planning would be remiss if attention were not given to backup and availability planning techniques. In order to be able to successfully recover critical business operations, the organization needs to be able to effectively and efficiently backup and restore both systems and data. Though many organizations are diligent about going through the process of creating backups, verification of recoverability from those backup methods is at least as important and is often overlooked. When the detailed recovery process for a given backup solution is thoroughly reviewed, some specific requirements will become obvious. One of the most important points to make when discussing backup with respect to disaster recovery and business continuity is ensuring that critical backup media is stored offsite. Further, that offsite location should be situated such that, during a disaster event, the organization can efficiently access the media with the purpose of taking it to a primary or secondary recovery location.

A further consideration beyond efficient access to the backup media being leveraged is the ability to actually restore the said media at either the primary or secondary recovery facility. Quickly procuring large high-end tape drives for reading special-purpose, high-speed, high-capacity tape solutions is untenable during most disasters. Yet many recovery solutions either simply ignore this fact or erroneously build the expectation of prompt acquisition into their MTTR calculations.

Due to the ever-shrinking MTD calculations at many organizations, with some systems now actually requiring Continuous Availability (an MTD of zero), organizations must often review their existing backup paradigms to determine whether the MTTR of the standard solution exceeds the MTD for the systems covered. If the MTTR is greater than the MTD, then an alternate backup or availability methodology must be employed. While traditional tape solutions are always getting faster and capable of holding more data, for some critical systems, tape-oriented backup and recovery solutions might not be viable because of the protracted recovery time associated with acquiring the necessary tapes and pulling the associated system image and/or data from the tapes.

Note

When considering the backup and availability of systems and data, be certain to address software licensing considerations. Though some vendors only require licenses for the total number of their product actively being used at one time, which could accommodate some recovery scenarios involving failover operations, others would require a full license for each system that might be used. Also, when recovering back to the primary computing facility, it is common to have both the primary and secondary systems online simultaneously, and, even if that is not typically the case, to consider whether the vendor expects a full license for both systems. Another point regarding licensing and recovery is that many vendors will allow cheaper licenses to cover the hot spare, hot standby, failover, or passive system in an active-passive cluster as long as only one of those systems will be processing at any given time. The complexities and nuances of individual vendors’ licensing terms are well beyond the scope of both this book and the CISSP® exam, but be certain to determine what the actual licensing needs are in order to legally satisfy recovery.