If you are backing up direct to tape, it's likely you're underfeeding your tape drives. The current generation of LTO4 tape drives (soon to be supplanted by LTO5) is theoretically capable of more than 120MBps of data write throughput, but few ever see that in real life. Mostly this is because there are very few backup sources that can support sustained read rates to match the tape drive's write performance. For example, a backup source consisting of a pair of SAS disks in a RAID1 array may be capable of raw throughput well beyond 120MBps in a lab environment, but for standard Windows-based file copies over a network, you'll rarely see rates greater than 60MBps. Because many tape drives become significantly less efficient when their buffers are empty, this becomes the root cause of most backup performance problems.
In other words, the problem isn't your tape drive; it's the storage in the servers you're backing up. Though there may not be a great deal you can do about this without investing heavily in a large, high-performance intermediate disk-to-disk backup solution, you have more options if you have a SAN. Though it will depend largely on the kind of SAN you have and what backup software you run, utilizing host backups -- which read directly from the SAN rather than over the network -- can be a great solution to this particularly vexing problem.
Matt Prigge is contributing editor to the InfoWorld Test Center, and the systems and network architect for the SymQuest Group, a consultancy based in Burlington, Vt.
Paul Venezia is senior contributing editor of the InfoWorld Test Center and writes The Deep End blog.
Originally published on InfoWorld. Click here to read the original story.