Most Tape Libraries Have Too Much Horsepower

It's human nature to gravitate toward the latest and greatest technology, but in the case of tape backup, most storage managers should probably resist the temptation. According to W. Curtis Preston, president of The Storage Group, one of the most common errors his clients make is to put tape drives in their backup that spin faster than their backup servers can sustain them.

Buying tape drives that are too fast for your environment leads to one of two things: If tape drives don't receive a continuous stream of data, they stop, back up and start up again. This scenario, called shoeshining, is hard on both drives and media, and slows down backups. Alternately, backup managers interleave multiple backup streams to a single tape, which can lead to problematic restores.

Yet manufacturers continue down a relentless path of building ever faster and larger tape drives. Last month, Quantum unveiled SDLT 600, the third generation of its super drive technology, which clocks in at 72MB/s (compressed) and can store up to 600GB. LTO-2 technology--which features 40MB/s to 80MB/s throughput and stores up to 400GB--has also started shipping.

According to Steve Berens, Quantum senior director of product marketing and strategy, both SDLT and LTO tape drives include workarounds to the shoeshining problem. SDLT drives are equipped with cache and an intelligent buffer algorithm, while LTO drives rely on adaptive motor speed. "The key is to optimize the backup, not de-optimize your backup," Berens says.

Still, Berens agrees that SDLT 600 is not for everyone. Equipped with Quantum's DLTSage diagnostic information, Quantum hopes to see SDLT 600 find its way into the upper reaches of the data center, in environments where tape drives such as StorageTek's 99x0 series dominate. To help customers pick the best tape drive for them, Quantum has posted a configuration tool on its dlttape.com Web site, which suggests a tape drive based on individual system parameters.