Hal Weiss, systems engineer at Baptist Memorial Healthcare in Memphis, tends his back-up and recovery environment like a gardener. And just as some plants require shade and others sun, not all applications require the same type of backup.

Weiss is helping Baptist contend with new federal regulations and exponentially increasing data volumes. And, like other hospitals, Baptist Memorial is moving away from paper and film to an electronic environment.

"We've told physicians to meet us on the Internet and we'll give them access to all their patient data, including views of X-rays and lab results, from the convenience of their home or office," Weiss says.

Baptist Memorial comprises 15 hospitals in three states - Arkansas, Tennessee and northern Mississippi. Storage has grown from 2T bytes in 2002 to 138T bytes by the middle of this year. Data is now growing at an 8T-byte clip per year and - to be compliant with the Health Insurance Portability and Accountability Act - must be maintained seven to 21 years, depending on the patient's age.

One of the problems with protecting this volume of data is that traditional schemas using physical tape don't work. "How are you going to back up 138 terabytes to physical tape?" Weiss says. "There's not enough hours in a day, no matter how many tape drives you have."

So Baptist uses multiple tiers of data protection, including host-based mirroring, a Copan virtual tape system, and traditional tape for deep archiving. But it still needed something else for its very complex applications that house data on multiple servers.

An example is Mckesson's Horizon Patient Folder, which relies on two servers that have to be synchronized - a database that keeps pointers to all the images that make up the patient folder and an image server that stores those folders. In Baptist's metropolitan environment, which comprises five hospitals, this application eats up 7.5T bytes of data. "If you tried to back that up on physical tape, it would take 20 days, and to restore it would be 40 days or more," Weiss says. Plus, the data would not be synchronized.

For this application, Weiss turned to Revivio's CPS 1200, a continuous data protection (CDP) system that lets companies restore data to any point in time and recover business applications in minutes.

Unlike snapshot technology, which takes snapshots at predetermined times, CDP systems capture every change made to a file and separately maintain a log and time stamp for every write made to disk. "The effect is that you can literally turn back the clock to any one of those changes," says Bill North, director of research for IDC's Storage Software service.

CDP technology has yet to hit the mainstream, and it's not a technology for everyone. "For users that require ultimate granularity in their recovery operations, CDP is the Holy Grail," says Pete Gerr, senior analyst at Enterprise Strategy Group. "But mainstream users are still somewhat hesitant to deploy the technology."

"We're at the early stages of market development for CDP," acknowledges Kirby Wadsworth, senior vice president of marketing for Revivio. Other vendors include Mendocino Software, Timespring Software and XOsoft.

Even so, a surprisingly large percentage of Enterprise Strategy Group survey respondents (63 percent) said they were familiar with CDP.

Baptist plans to expand Revivio in 2006 to cover its clinical document applications. By 2007, Weiss hopes to replicate the Revivio backup to another Revivio device at an offsite location for disaster-protection.

But this wouldn't be your traditional asynchronous replication. "With traditional replication, you might get a recovery point every four to six hours," Wadsworth says. "With our systems, you could have a failure at noon in Boston, and at 12:01:01 in Chicago, you could effect a restoration of the Boston data, and Chicago would have an exact copy."