Incremental improvement: 'Synthetic' backups save time, money

Computerworld - Bernard Shen, a technology consultant at aerospace company BAE Systems North America Inc., went from shipping 1,200 data archive tapes to an off-site storage facility every 90 days to sending just 200 over the same time period. He did it by storing only incremental changes to his company's data.
Shen says the business case for incremental data backup was a no-brainer, but selling the idea to his IT team wasn't easy. "There is a tremendous amount of skepticism around it," he says.
While Rockville, Md.-based BAE saves incremental changes across its 25TB storage-area network (SAN), those data slices can be combined with previous full-server backups to create what's known as a synthetic backup, from which a systems administrator can then restore a file or application if it becomes corrupted or data is lost.
Although Shen has eliminated full backups on his file servers with incremental backups, he still performs them on his database servers because the technology he uses doesn't support block-level changes.
Adoption of synthetic backup is increasing rapidly because it saves systems administrators from having to shut down application servers to perform full backups and it reduces the amount of data backed up to disk and archive tapes. The changed data that's saved amounts to less than 10% of all data, according to analysts.
Relatively inexpensive disk-to-disk or disk-to-disk-to-tape architectures are rapidly gaining acceptance by IT organizations facing shrinking backup windows, according to Mike Kahn, an analyst at The Clipper Group in Wellesley, Mass.
The pain points users are addressing with synthetic backups are their recovery point objective (RPO), their recovery time objective (RTO) and the ever-growing backup window, analysts say. RTO speaks to how long it takes an organization to be up and running after a disaster or data loss, and RPO refers to how old the recovered data will be.
Ghyslain Boisvert, executive director of the high-performance computing laboratory at the University of Montreal, uses Time Navigator Server from Atempo Inc. in Palo Alto, Calif. With it, he creates a full backup of research data off-line from incremental backups made to tape libraries from Storage Technology Corp. and Dell Inc.
Boisvert said it still takes him seven hours to perform a synthetic full backup from incrementals for about 660GB of daily data -- not much shorter than the 10 to 12 hours standard full backups take. But the synthetic backup has no effect on his production servers because they no longer need to be shut down as they did during backup to a tape library.
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