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
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Alex Lazarevich | Systems Administrator | Imaging Technology Group
Alex Lazarevich | Systems Administrator | Imaging Technology Group
Beckman Institute | University of Illinois | www.itg.uiuc.edu
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