If you can’t measure it, you can’t manage it. And since managing data recovery is now the focal point of most Disaster Recovery and Business Continuance plans, the need for metrics that can measure the process are growing in importance.
The three dimensions of data recovery measurement are:
- Recovery Time Objective (RTO): How fast a system is capable of recovering the data and application it is designed to protect.
RTO is important because it corresponds to the maximum amount of down time a business can tolerate. RTO is not about data loss, but rather about getting back to business as quickly as possible.
Today, we frequently encounter companies that have set a zero RTO. Zero RTO objectives exist in mission-critical applications in a number of industries. According to an Enterprise Strategy Group survey of mid-tier customers:
· Five percent could not tolerate any downtime for critical applications and would experience significant revenue loss immediately.
· Twenty percent could tolerate only less than one hour of downtime.
· Thirty-three percent could tolerate between one and four hours of downtime.
· 58 percent would have their businesses significantly impacted by four hours or less of downtime.
- Recovery Point Objective (RPO): The time gap between the last failure and the point-in-time to which data can be recovered. The smaller the gap, the less data is lost.
RPO is important because it measures how much data you are comfortable throwing away. There may be mission- or business-critical applications that demand zero data loss and therefore require an RPO of zero. One lesson these companies have learned is an RPO of zero can be extremely expensive to achieve.
Therefore, many companies define a range of RPOs depending on the application. Not infrequently, businesses can sustain some amount of data loss and accept the associated cost.
- Finally, Recovery Granularity Objective (RGO) is a measure of the level at which data recovery needs to take place whether at the file, block or transaction level.
RGO is important because the cost of providing finer-grained recovery may become out of sync with the value of the data being recovered. An emerging technology called Continuous Data Protection (CDP) is sometimes touted as a way for businesses to capture all changes to data as they occur, with sufficient granularity to roll back to any point in time. For some applications this may be a perfect match, while for others it may be overkill.
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Bob Farkaly,
Vice President, Worldwide Sales