When you hear the term "continuous data protection" (CDP), you might think of giant, comprehensive—and expensive—solutions that only large-enterprise players can afford. A few years ago when the technology first began to gain traction, that image might have been accurate. "True" CDP solutions were traditionally complex and came with a proportionately hefty price tag. But now vendors are stepping up to provide complete data protection solutions for businesses of every size and budget.
What Does CDP Do for You?
Continuous data protection is different from simply creating a backup. Typical tape backup involves making a periodic copy of data to a tape medium, then taking that tape to a secure place so that if your organization needs to recover data from a particular time period, it can do so. But such a process can leave enormous gaps in time during which you might lose thousands of data transactions.
The idea behind CDP is to incorporate backup, archive, and disaster-recovery functions into a single solution that works automatically. With CDP, there are minimal gaps in the data that's backed up. A CDP solution makes an automatic, continuous copy of all data at the block or file level, capturing data transactions at short intervals of a few minutes (as in the case of near-CDP solutions) or in a streaming fashion so that every second of data activity is accounted for (as in the case of true CDP solutions). The level of protection that you'll look for depends on how much data latency your organization can tolerate. If you have a moderate amount of activity on your servers and you can handle the possibility of a gap in your data of a couple of minutes, a near-CDP solution might meet your needs. If your servers are high volume and you can't afford to lose even a few transactions, then a true CDP solution will be what you need.
The other side of the data protection coin is recovery: When a server problem occurs, you need to be able to quickly recover and use your data. CDP solutions are designed to provide seamless, nearly instant data recovery. Ideally, your database users wouldn't notice that a problem had occurred; data recovery would be immediate and availability would be uninterrupted. However, you'll find that data latency allowances vary among solutions. In addition, data recovery granularity varies depending on the solution, from recovery of data volumes to individual files or application objects.
Points to Consider
The architecture and features of CDP solutions vary, but as you research solutions, keep in mind several important considerations. First you'll need to decide whether you should employ a host-based or storage-based solution—that is, whether the CDP software runs on the server you want to protect or on a SAN controller. For a clear explanation of what these two options mean, see Paul Robichaux's Exchange & Outlook Pro VIP article "Exchange CDP," http://www.sqlmag.com, InstantDoc ID 95234. As Robichaux notes, host-based products can be configured to various levels of recovery granularity. Storage-based solutions have the advantage of minimal interference with the workings of your databases because no drivers or components are installed on your servers.
You'll also want to consider what features are best for your organization. Are you looking for an enterprise solution, or are you working from a small or midsize shop? And how do you qualify the size and scope of your business? One vendor in our list defines a "midmarket" organization as one that brings in revenue of between $50 million and $1 billion—does your perception of your organization match vendors' perceptions? Are you working in a Microsoft-only or heterogeneous environment? Do you need support for multiple backup devices? Do you want to let users initiate their own restores? Do you need your CDP operations to be completely automated and transparent? In the table on the following pages, you can peruse a sampling of various solutions and compare the features that they offer.
Something for Everyone
CDP isn't just for the big guys anymore. Although you can still find large-scale solutions that cost many thousands of dollars, you'll also find software solutions that start at a few thousand dollars, subscription-style services that are provided for a monthly fee, and solutions that are licensed on a per-seat basis. So, regardless of your organization's size or financial constraints, you can find a CDP solution that will protect your data.