By W. Curtis Preston
Continuous data protection (CDP) technology is the future of data backup and recovery, even though early continuous data protection products didn't live up to the hype when
Many people viewed continuous data protection as the Star Trek of the backup industry -- a great idea before its time. Star Trek, maybe not fully understood when it first aired, was canceled after three seasons. Similarly, many people thought continuous data protection was a solution looking for a problem, and most shops could meet their backup and recovery requirements without completely changing the way they did backups, which was required with continuous data protection.
There are now several continuous data protection products that are doing quite well, so what changed? Perhaps the most important change is that most of today's CDP products are offered by mainstream backup vendors. In fact, almost every major backup software company now has a CDP offering. Users don't have to accept an all-new paradigm and an all-new backup vendor to get CDP functionality.
The next big reason for the resurgence of CDP is that the products have come a long way since they first appeared on the market. For example, you no longer have to choose between an on-site and off-site copy; you can have both with a single product. The "CDP product sampler" chart below looks at some popular CDP products.
Today's successful CDP systems also know a lot more about the data they're backing up. They offer integration points with many popular applications such as Microsoft Exchange, Oracle and SQL Server. While a true CDP product doesn't need to create snapshots and can recover to any point in time, this integration allows the application or backup system administrator to create points in time where a known good copy of the data resides. Administrators may opt to not use these known good recovery points during a recovery operation, but they have the peace of mind of knowing they're there.
And, like Star Trek, it may be time for CDP: The Next Generation. Some servers have grown tremendously in just the last few years, and the recovery time objectives (RTOs) and recovery point objectives (RPOs) for those large servers have become more stringent. Consider a 300 TB database that's mission critical for a company, with potentially millions of people using their service 24/7. The database backup system has to provide an instant recovery with no loss of records; this is only possible with CDP.
With CDP, a company can have on-site and off-site copies of their data without ever touching a tape, thus avoiding encryption entirely.
Also figuring into the picture are data loss notification laws, enacted by 35 states and the European Union, that require many companies to add encryption systems to allow them to safely transport personal information on backup tapes. However, encryption systems can be expensive, cause slow backups and require management of encryption keys. With CDP, a company can have on-site and off-site copies of their data without ever touching a tape, thus avoiding encryption entirely.
Server virtualization has taken off during the last few years, and the technology could benefit from continuous data protection. While you may not have individual servers with data stores in the double-digit terabyte range, it's possible the storage used by VMware, Microsoft Hyper-V or Citrix Systems XenServer is indeed that big. Consider what would happen if a 15 TB storage array containing virtual machine (VM) images suddenly disappeared -- it could take out dozens or hundreds of virtual machines. Couple that with the fact that backing up and recovering those virtual machines using traditional methods is one of the more difficult tasks a backup system architect has to consider. Physics is your enemy; 20 virtual machines on a single physical machine perform like one physical machine during backup.
But if physics is your enemy, CDP is your best friend. A good CDP product places no more load on your VM than a typical virus protection package, and it's able to recover one or all of your VMs instantaneously with no data loss. Server virtualization alone could herald the comeback of continuous data protection.
EDITOR'S TIP: Click here to read this next part of this guide on continuous data protection software.
W. Curtis Preston is an executive editor in TechTarget's Storage Media Group and an independent backup expert.
This article was previously published in Storage magazine.
This was first published in October 2010