While both approaches involve capturing a system's state at a given moment in time, snapshotting does this at pre-determined set points, which could be every 10 minutes, once an hour or three times a day. Therefore, if a fault occurs, any data generated since the last snapshot took place will be lost, as it would with traditional forms of backup.
Continuous data protection backs up data every time a change is made, which means a system can be restored to the point where the last modification took place. Because CDP keeps a record of every transaction, if the system becomes corrupted or is infected by a virus, it's possible to recover it to the most recent clean copy.
CDP currently comes in two main forms: software-based, with agents that run on designated servers, or hardware-based appliances that can be used either in-band (in the data path) or out-of-band (outside the data path).
Most of the large backup vendors operate in the CDP space, with key offerings, including, CA's XOsoft, EMC's RecoverPoint, IBM's Tivoli Storage Manager, Microsoft's Data Protection Manager and Symantec's Veritas NetBackup. Other important players include Barracuda Networks with Yosemite Desktop/Laptop Backup and FalconStor Software with its Continuous Data Protector.
This was first published in September 2009