Hmm, guess I don't agree that disks are cheaper than tape libraries. I've been working for some time on pricing out a 1-terabyte set of storage, and here's roughly what I've come up with:
1TB of disks, SCSI RAID array: 4.5 to 6 cents per MB 1TB of DVD-RAM jukebox + media: 2.6 to 3 cents per MB
The price for the DVD-RAM library solution above includes the software & drivers to control the library. These prices are from real quotes, maybe two months old at most.
Tape media (DLT7k) is way cheaper than DVD-RAM media, by the way. Take the following with a grain of salt, since I'm doing it on the fly here, but I'm seeing DVD-RAM media at the "old" 2.6GB density (single-sided), including a magazine, coming out at 1.2 cent per MB ($30 per disk).
DLT7k media is more like 0.1 cents per MB ($65 per cartridge, where we're seeing capacities running about 50 to 55GB per tape). Our ATL P1000 library with 2 drives was around $30k, if I remember right. Add that to a full complement of media (30 tapes), giving 1.6TB capacity, total cost comes to about $32 or $33k. Even if it's higher than that, it's still got a long way to go before it gets to the $40k we've been quoted seeing for 1 TB of RAID.
Plus I can take the tapes (or DVD-RAM disks) out of my library and buy more media, extending my off-line capacity even more cheaply.
Dunno, maybe the prices I'm seeing are out of whack, but tape just still seems cheaper.
Regards,