Continuous Data Protection
Although there has been a high level of interest in the topic of Continuous Data Protection (CDP) in the storage industry for the last few years, an authoritative definition of CDP remains something of a moving target.
Some vendors intend CDP to mean the ability to restore data from any point in time. Others may describe it as the ability to get an application back on line quickly in a consistent form while minimizing the loss of data. Still others may define CDP as simply “snapshots plus data replication.”
A useful working definition is the one provided by the CDP Special Interest Group of the Storage Network Industry Association (SNIA):
“A methodology that continuously captures or tracks data modifications and stores changes independently of the primary data, enabling recovery points from any point in the past. CDP systems may be block, file, or application-based and can provide fine granularities of restorable objects to infinitely variable recovery points.
Despite all of the differing ideas on the definition of CDP, there are a relatively clear set of conditions, characteristics, and metrics that set the boundaries for what a CDP solution must exhibit in order for it to be effective, or in other words, “true CDP.”
Although there are many different ideas of what CDP is, it is clear that in order for a CDP solution to be most effective, it must protect data in a manner that is both time-addressable and event-addressable - in short, to provide nearly infinite RPO and low RTO.