From: Chris Mauritz chrism@imntv.com
I've found that backing up to another disk to be both faster and more practical. We've got a number of multi-terabyte RAID arrays to store uncompressed video. Backing all that data up to tape just isn't a tenable solution. So we've bitten the bullet and built an extra larger multi-terabyte array to do online backups. Periodically we do snapshots of the data on that backup array (like you do on a netapp filer). That system works well for us. It wouldn't cover us if the building burned down so the next step is an offsite mirrored array.
If you have the dough, Virtual Tape Libraries (VTLs) are the ultimate in flexiblity. Although there are many solutions, nearly all of them are the Red Hat Linux 7.3 + FalconStor Software combination.
Although EMC, IBM and others have traditionally use standard disk arrays as they use for other solutions (with the software slapped on), Copan Systems' hardware solution is designed specifically for VTL and VTL-only. The density, power/thermal, cost and other considerations are rather interesting.
-- Bryan J. Smith mailto:b.j.smith@ieee.org