I started a thread a few weeks ago about compressed files, in particular files from Quest's LiteSpeed product that does compressed dumps to disk of SQL DB's. In our environment, the DBA's are using Level 4 compression of that product and it was producing 60 GB dump/compressed files. I found out with some experimentation that TSM would take twice as long to backup a 60 GB compressed file as a 60 GB uncompressed file.
BTW: Have TSM server 5.5.2.1 on AIX 5.3 with 3584 Library - and LTO2 drives for this situation. This got me to thinking and looking harder at some other backups I have. One application has compressed image files on disk storage that I backup to TSM. Another totally different App does it's internal backup by dumping a propietary DB and some other stuff into a single 50 GB Zip file. I had noticed that these seem slow, but now looked closer. Basically from what I see TSM takes twice as long to "process" a compressed file as the same size uncompressed file. Not using TSM compression anywhere - except on tape. I tried sending to the uncompressed tape - ULTRIUM2 as opposed to ULTRIUM2C and no difference in speed. This "twice as long" thing is no matter how you are backing up or copying. Client direct to tape, client to disk oool, disk pool to tape, tape to tape or VTL to tape. Doesn't matter - same speed. So, why does TSM take twice as long? Having a hard time with each read determining whether compressed or not or what? I've never heard of this before, only that if you use TSM client compression you have performance issues on the client - makes sense. Thanks, David Longo ##################################### This message is for the named person's use only. It may contain private, proprietary, or legally privileged information. No privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it, and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient. Health First reserves the right to monitor all e-mail communications through its networks. Any views or opinions expressed in this message are solely those of the individual sender, except (1) where the message states such views or opinions are on behalf of a particular entity; and (2) the sender is authorized by the entity to give such views or opinions. #####################################
