Hot Diggety! Orville Lantto was rumored to have written: > A 72 drive, 10 I/O slot 3584 library will hold 2207 cartridges. with 175 > GB/cartridge that works out to 6 libraries.
Aye, in terms of tape capacity. However, if you have a requirement that it finish an entire full backup in a single day -- say, 20 hours...and you get between 15-30 MB/sec for HW compressed writes with the LTO drives. So we pick a common number that's actually sustainable in real life: 22.5 MB/sec. 22.5 MB/sec * 72,000 seconds (20 hrs) * 72 drives * 6 libraries = 683,438 TB, or about 32.6% of 2 PB. Therefore you need 3 times the original number of 6 libraries, and that's assuming you can keep up this rate constantly for every single second of 20 hours. 18 fully decked out 3584 libraries would be something to behold, I think ;) That'd span 106 frames and 1,296 LTO drives. A single full backup would run about $18M (list price) worth of tapes in that kind of configuration. I'd like to work for a place that can afford it! Even after deep discounting, that's still $8-10M worth of tapes. -Dan
