Hi,

In our setup we are using disk caching. The only time we are seeing
performance issues is when a large backup is overloading the disk pool
multiple times in one backup window due to unscheduled full back-ups.

When the disk pool is of sufficient size to hold at least one backup run
and your backup server isn't at its max performance capacity, you can
easily turn caching on (and off if you run into performance problems).

The other thing we do, is migration as a last step in de daily
processes. We run a script that:
1st) backup diskp > copyp;
2e) backup tapep > copyp;
Last) migration.

Hope this will help,

Regards,

Karel

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
PEEK, CHRISTOPHER
Sent: dinsdag 10 mei 2005 17:39
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Keeping Disk Copies of Files - Storage Pool Cache or ????

I am trying to implement a backup process where a complete set of file
copies are kept on disk in addition to tape.  Our current process is a
very traditional basic setup with backups going to a single disk storage
pool that then migrates to tape during the day.  After the migration
completes, the process then makes multiple tape copies for offsite and
onsite vault storage.

I have the following questions:
1) What is the best process to keep a disk based version of the most
recent file copy?  

2) Is it enabling the cache for the disk storage pool and increasing the
storage pool size to hold the copies; or is it better to go with a disk
to tape (d2t)/disk to disk to tape (dd2t) dedicated device?

3) Is anyone using the storage pool cache?  What is the size of the
storage pool and how has performance been impacted?





Just for reference, here are the details of our TSM environment.

Current TSM Server OS:          AIX 5.1 ML 07
Current TSM Server Ver:         5.2.2.14
Disk Storage:                   DS4400 (FastT 700) SAN - Fibre Channel
Tape Storage:                   3583-L72 with 3 LTO2 fibre drives