A problem I've started noticing lately. You can buy a 60 gigabyte IDE hard drive for $220 as of the time of this writeup. However, backup equipment that can back up this much data is still ridiculously expensive. It is actually cheaper to simply mirror the data on another disk in a hot-swappable drive bay and store it in a safe place than to buy a tape drive.

Hopefully the prices on decent backup equipment will come down soon to match that of disk storage. Remember when tape storage was cheaper than disk? Not anymore, bub.

Not only are backup devices expensive (for instance, an Exabyte Mammoth 2 drive, that can backup 60GB uncompressed, is around $2000), but they aren't fast enough to back up large arrays in any reasonable backup window. While mirroring and RAID are good alternatives, you still need tape for disaster recovery and the like, but if you have terabytes of storage, you're going to have a hard time backing it up in 8 hours, say.

If you really care about data integrity an option is to have a SAN with a mirrored set of RAID disks, each in a different location. Ideally in different buildings. Ideally in different towns.

(February, 2003): It has been realized that a 120GB IDE drive is only marginally more expensive than a 110GB Super DLT tape cartridge. If only someone would make a library that had hard drives on carriers. . .