We are going to try disk only backups using ATA storage.  We've decided to
use use a FILE device class for the ATA storage pool and do the backups
directly to the ATA storage pool.  We will back up the data to a copy
storage pool defined on a 3494 tape library.  I know that this will involve
running reclamation on the ATA storage pool but we felt using a DISK device
class would waste to much storage because of fragmentation.
Jim Sporer
University of Wisconsin

 At 10:05 PM 5/28/2004 -0400, you wrote:

We recently had a presentation from EMC.  During this presentation
they discussed their new DL700
virtual tape library.  It got people talking about a long
term strategy of moving to a all disk based backup system.  So we
started thinking of the pros and cons of how to go about setting up TSM
for a disk based backup system.

Here are some initial thought on ways to configure TSM for D2D
backups.  We would be very interested in your thoughts/comments.  I
doubt we are the only people thinking about this topic.

1)Purchase a very large disk system (ata drives?) and put storage pools on
them.
    - use a standard DISK device pool for backups
        - how to reclaim space?  do you even need to?
        - fragmentation problems?
        - multiple node access concurrently
    - use a FILE device based pool
        - single node access per disk file volume
        - need to run reclamation
        - still stage to disk and migrate to FILE device based pool?
    - use a tape copy pool for offsite and backup
    - use a offsite disk pool somehow
        - iscsi over lan or fc if close enough (enough throughput?)
        - other?
    - must use client compression to get data compressed
        - we mostly don't do this today

2)  Purchase a virtual tape system like the DL700
    (bundle of a EMC Clariion and a FalconStor vts appliance)
    - provides compression for data
    - appliance is responsible for layout and use of disk space
    - can copy a virtual tape to a real physical tape for offsite storage


Thanks

Rick