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Tiered data recovery
You don't need 100% of your production data at the remote location for a partial or near full recovery--just enough to put you back in business. The effort, therefore, involves identifying components that can be left behind or those that can be reconstructed using relational data. Databases are the most common examples here. File and print services are another. Keep in mind that we're not talking about losing this data for good; we're only deferring its recovery to a later point in time, perhaps using tape.
Just as production storage is tiered using service-level agreements, data recovery can be offered in a tiered manner and tied into the overall storage service model. Data- supporting applications that form the backbone of your business can be replicated in a synchronous or near-synchronous manner that's capable of providing "zero transactional loss." Second-tier applications may be replicated asynchronously in an "always on" or periodic "sync-split-sync" manner. Those approaches can provide an RPO in which losing a few transactions is considered normal or not business critical. Moreover, the lost information can be reconstructed using indirect methods or a reload of data from sources outside of your company. Of course, if the application data can withstand a few days of downtime, it's a candidate for recovery by tape. An important technological innovation that has only recently been applied to data storage is quality of service
It's easy to assume that just because you have a data recovery solution in place it will work in the manner envisioned by your DR strategy. But the old adage of practice makes perfect is particularly appropriate for a DR plan: Put it through its paces and make it work for you.
This was first published in August 2007