Continuous data protection (CDP) allows IT pros to turn back the clock -- at least as far as data is concerned. The technology is essentially replication with the ability to roll back to a specific past moment in time, as CDP maintains a record of every single write and tracks blocks that have changed, according to W. Curtis Preston, founder of Truth in IT & BackupCentral.com.
"Whenever I sit down with my DR buddies, I'm a backup guy, not necessarily a DR guy… and they always want to go to replication," said Preston. "They want to ignore tape, which is fine, but they want to completely ignore anything that sounds like backup, including CDP or near-CDP, and go straight to replication. What if there's corruption? Replication just wipes out both sites. I've always had difficulty with that idea."
Preston noted CDP is replication with a record. Unlike replication, which would allow an error to be replicated from one site to another, CDP allows users to roll back to a point in time before the error occurred.
"CDP allows you to say, 'Go back to three minutes ago, and everything will be fine,'" said Preston.
RPO can be zero with CDP so long as replication is synchronous. Otherwise, asynchronous replication will mean the RPO will be a few moments behind when the error occurred -- but it shouldn't be a large gap, according to Preston.
"So RTO is basically zero … because you're basically dialing a knob and you're fixing blocks and you're done. And RPO is whatever you want to be -- literally seconds," said Preston.