Huh? Have as many dbvols as you need! You're going to be running for a LOT longer than you are going to be restarting, and you want it to run as fast as possible. TSM is really quite stable, so optimize it for faster running, not for faster restart and recovery. So what if it takes a couple minutes to start?
Conicidentally, though, your number of 8 dbvols is not bad for a 48GB database. Just don't feel like it's a limit if your database grows. I have 26 database volumes, mirrored by TSM, for a total of 52. Depends on your physical configuration. You probably want about 2 dbvols per physical disk. If you've got a RAID black box of some sort, still do that arithmetic, though the TSM DB really runs best on JBOD disks mirrored by the TSM server itself. (Many RAID boxes can be configured as JBOD.) In the restart and recovery aspect, you're interested in safety a lot more than speed. TSM mirroring gives you a better chance of recovering a damaged database than does OS mirroring or RAID-box mirroring, and it runs faster, too. Avoid RAID5 for the DB at all cost - parity on writes will kill performance. RAID10 is tolerable though not as good as JBOD with TSM mirroring. The TSM Log is a very different animal. Remember that the log can be no larger than 13GB. Since you always want to leave yourself room for an emergency log expansion in case it fills up on a Dark And Stormy Night, you should never make it larger than 12GB. Number of volumes is less critical on the log, since it is accessed round-robin, instead of randomly like the database. I have 3x4GB logvols. With the log you seriously want TSM mirroring. The chances of recovery after a mishap are a lot better with a TSM-mirrored log, than with an OS or RAID-box mirrored log. I've been there with a damaged log, and the whole database was saved by the ability to set MIRRORREAD LOG VERIFY in order to recover. You can't do that with OS or RAID-box mirroring. Roger Deschner University of Illinois at Chicago [EMAIL PROTECTED] =========An optimist is someone who says a glass is half full.========== ===A pessimist says it's half empty. An engineering consultant says,==== ========"Looks like you've got twice as much glass as you need."======== On Fri, 12 Jan 2007, Dierk Harbort wrote: > >I am working on a new design of our tsm environment - a lot of changes in >sight this year. So here a litte question to check my ideas for the new >design: > >IBM support told me, that it would be the best to have not more than about >6-8 diskvolumes for the tsm database, due to the recovery mode on tsm >server start. > >Do you agree? Are there any recommendations like this for the tsm >logvolumes? I am thinking about 8x 6145MB dbvolumes and 8x 4097MB >logvolumes. > >Or any other things to consider? > > >TIA, >Dierk >
