Joe, I'd add that you need to consider a safety valve of leaving out 1/2 to 1 gb of your log space so you have something to add if (when) you do someday run out of log space. If you run out of log space -in rollforward logging- your TSM server will stop until you either extend the log (hence the hold back) or restore the TSM database!
You need enough of a safety valve to enable you to get your TSM server back up and complete a database backup without again filling the log. I setup customers to hold back 1 gb of pre-allocated space. Immediately upon the subsequent database backup completing (and reducing the log to zero) I then recommend to immediately remove the safety valve log volume. Steffan ----- Original Message ----- From: "William F. Colwell" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, February 28, 2002 1:13 PM Subject: Re: logmode/bufpoolsize/mpthreading > Hi Joe, > > At 03:39 PM 2/28/2002 -0500, you wrote: > >Environment: > >Server: 4.1.3.0 > >Platform: S390 > > > >1. Logmode: We're going to change the Logmode from Normal to Roll Forward. What determines the amount of disk I'll require? > > You need enough log space to hold all the db changes between scheduled db backups. So it depends > on how much activity you have and when you want db backups to occur. You should also set the > dbbackuptrigger as a safety valve; it will kick off a dbb when the log gets nn% full. I am on s/390 also; > I set the trigger up to direct incremental dbb's to sms managed disk. My log is 7,146 megs; if you upgrade > the server code 4.2.(1.9) you can make the log more than 5.3GB, up to 13GB. > > You can do a 'q log f=d' and monitor the cumulative consumption value to see how much you > need for a day or between scheduled db backups. > > >2. Bufpoolsize: We're going to increase from 24576K to ?. What's the determining factor? > > Monitor the cache hit % in 'q db f=d'. The rule of thumb is to get it up to 98%. My bufpoolsize is > 262144k. You can dynamically changes this with the setopt command. > > > >3. Mpthreading: We're going to turn it on. Are there any considerations I should concern myself with? > > Can't say much about mpthreading; my processor has only 1 engine, but tivoli recommended it > anyway, so I turned it on. > > >None of this info is in the manual that I'm aware of. I get a log of "try this" form Tivoli support. Unfortunately, I don't work in an environment where I can "try this" without first knowing what > >the repercussions are. > > > > > >Regards, > >Joe Wholey > >TGA Distributed Data Services > >Merrill Lynch > >Phone: 212-647-3018 > >Page: 888-637-7450 > >E-mail: [EMAIL PROTECTED] > > ---------- > Bill Colwell > C. S. Draper Lab > Cambridge Ma.
