One thing I have seen every now and then, is when a large file spans multi-volumes, it will only get reported in utilization on one of the tapes, but when query the contents of volumes, it will show up as on both.
David N. Reiss TSM Support Engineer [EMAIL PROTECTED] 407-736-3912 -----Original Message----- From: Price, Bob R. [mailto:[EMAIL PROTECTED]] Sent: Wednesday, September 25, 2002 10:45 AM To: [EMAIL PROTECTED] Subject: Under-utilized tape volumes Can anyone share some understanding of the follow issue? I have several tapes that appear to be grossly under-utilized. Tapes marked FULL (and even 100% utilized) that have 50GB-60GB capacity figures on a 100GB AIT3 cartridge. Most full tapes show 90-110GB and a few where compression is good shows up to 400GB. My concern is with the 50-60GB ones. What can cause such behavior? I have a few theories, but cannot pin anything down definitively. My theories: 1) On backups that are directed to skip the disk pool and write directly to tape, changing files that are retried do not reposition the tape, but instead continue writing causing large amounts of "unused" tape. This explains primary tape pools, but not copy pool tapes which show similar under-utilized values. 2) Again, on backups that are directed to skip the disk pool and write directly to tape, stopped tape motion could conceivably cause tape area to be skipped on tape motion start-up. I really have no evidence if this actually occurs, but it is a thought. 3) File meta-data is written to tape and not the TSM database along with the file data and is not reported in the capacity figure. I can almost belive that this could take up 50% of the space on selected clients. Any comments on the above theories, especially arguments why they cannot be true are welcome. As are those comments expousing new theories or known facts. Bob Price TSM / ADSM Administrator Marconi Services (412) 374-3247 WIN 284-3247 Fax: (412) 374-6371 Email: [EMAIL PROTECTED]
