Yep, you can do it. Overland also sells a virtual tape library, but I don't know about their prices, and so do other vendors. It is basically a bunch of disk, but looks like tapes.
Why is virtual tape so expensive? Well, IMHO ;) if folks will buy it at that price, then they will sell it!!! TSM doesn't have to have it, but there may be some reasons why it is good. I am sure someone can straighten me out on it! But you can set up a JBOD of any size with a file system on it. You can use it as a disk pool, or, if you are having some tapes still, you might take some of it and define some serial storage on disk. It will process just like tapes, just a lot faster. Keeping your disk and on-site 'tape' pool on disk devices is just fine, if you like its reliability! To get stuff off site, I like keeping tapes. $/gig, tapes are pretty cheap and pretty reliable. If you have the tape bandwidth, I would like an on-site copypool and an offsite copypool on tape. But that may just be my belt and suspenders conservatism. ... Enjoy, JC -----Original Message----- From: Alexander Lazarevich [mailto:[EMAIL PROTECTED] Sent: Friday, September 24, 2004 5:17 PM To: [EMAIL PROTECTED] Subject: direct attached disk (DAS) at a tape library? We have TSM 5.1.6.5 on win2k server. library is overland neo 4100 (60 tape capacity) with 2 X HP LTO-2 drives. We need another 12TB of backup capacity. We are considering getting something other that another tape library. Couldn't we buy a couple of 6.4TB SCSI-SATA RAID DAS devices, and attach that to our backup host via SCSI, and start using that DAS as one big disk(tape)? We would just tell TSM that the big disk is some massive spool, or even a tape. We could even buy several of the DAS units, and just keep adding them as spool (or tape) disks on the SCSI chain. This would give us FAST backup and restore. Why do we need tapes? I know there are disk systems like the Reo, which is just a DAS RAID that does tape virtualization, but those things cost 3 times as much as a regular DAS. Why is tape virtualization so expensive? Why do we need tape virtualization? Is there something about how TSM handles disks vs. tapes, that makes using DAS impossible, or not a good idea? We are not too worried about reliability. We think we can configure multiple RAID arrays on the devices so that we lessen the chance of disk failure causing backup data loss. There must be some things we don't realize that tape virtualization gives us that a bunch of DAS disks won't. Price isn't it though, because we can get 13TB of DAS for 24K. The equivalent in LTO-2 tape (with library) costs 35K. And Disk to Disk backup is even more, like 44K! The only disadvantage we can come up with are that we can't remove tapes. But we don't remove tapes anyway. Please tell me why we shouldn't just attach a big 13TB DAS to our TSM host, and start using that as the main backup disk. Thanks, Alex --- --- Alex Lazarevich | Systems Administrator | Imaging Technology Group Beckman Institute | University of Illinois | www.itg.uiuc.edu --- ---
