Re: Logical Logs Size
Hi Mary, If you send me your configuration file and size of your database server RAM,I'd send you a set of tuned combination of kernel and OnLine parameters. --Babak >From: mary@anasazi.com (Mary Curtis) >To: informix-list@iiug.org >Subject: Logical Logs Size >Date: 18 Nov 1998 16:16:38 -0700 >Reply-To: mary@anasazi.com (Mary Curtis) > > >Forgive me if my question has been discussed recently or repeatedly. >I haven't been able to read this newsgroup for ages, but would >appreicate your input as I have a limited amount of time to research >my questions. Please respond via email if possible, thanks for your >help .... Mary Curtis (mary@rez.com) > >We are running a large OLTP application on a SUN 10000 platform. We >have DLTs (jutebox like) tape media. In the past we have always run >continuous logging to tape (DAT tape drives). Continuous logging to >the DLTs is no longer the preferred method. We plan to run SUN's >NetBackup utility to backup the Informix logs when a pre-determined >number are full. > >Our experience has been with running small sized logical logs in our >continuous logging environment in the past (2k to 8k in size). At >approximately 4k size, our application will fill a log on the system >we are discussing in as little as 2 minutes and in as long as 30 minutes >given the varying times of the day and the load. > >The jutebox can't keep up with the logs filling in minutes, the >storage media is meant for less often backups, but to stream a lot of >information quickly to the tapes. > >The primary question, HOW BIG TO MAKE THE LOGICAL LOGS? Our system >administration group would like to see 50 megabyte logs. That's way >too much shared memory for me, or is it?? > >I'm looking for experience and recommendations on suggested "larger" >sized logs. Please also comment on the following concerns if you can: > > - shared memory (allocating to a bundle to large logs?) > - long transactions (increasing the log sizes, have you decreased > the long transaction high water marks? We're > at 50/60 for LTXHWM/LTXEHWM) > - recovery (as long as checkpoints are in line, are you > safe? I've been in recovery on a long > transaction and hence my concern above about > rolling back forever and a day on a long txn) > - checkpoints (any special considerations? We currently > checkpoint at 150secs, duration usually 0-3 > seconds, no complaints) > - physical log size (any special considerations when increasing > logical log size?) > >Anything else you think of, please share your experience. > >Mary Curtis (mary@rez.com) >Sr. DBA - Rezsolutins, Inc. ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com