Re: Shared Memory Parameters?

Posted in 2000

Mark D. Stock — Wed, 16 Feb 2000 22:09:07 +0000 — source: Informix-list mailing list archive (1991-1998)

Calvin Shoults wrote: > > I am working with an existing database that has some onconfig parameters > that I am questioning. > > One of our problems is extents, but another reason we get hammered during > the day might be the following shm parameters. What's wrong with the extents? What problems do you have when you 'get hammered'? > OL Engine Vers. 7.31 on HP 9000 > Aprx. 400-600 users > Database - 14 gig How much memory? > 6 - CPUS Is this a database server only, or does it run apps as well? 6 CPUs might be enough for 600 users on a DB server, but sounds a little low for 600 apps as well. Are the CPUs flat out or coping fine? > 21 chunks used for database This isn't so critical as how many disks? These chunks might all be on one disk. Then you would have problems. ;-) > # Locks - 200,000 Sounds a bit small for 600 users, but depends on usage. > # Buffers - 300,000 Sounds about right, but depends on usage. > # NUMAIOVPS - 56 I guess with HP, KAIO is not an option? How was this number determined? > # PHYSBUFF - 1024 > # LOGBUFF - 128 > # LOGMAX - 50 Sounds a bit small for OLTP, but depends how big the logs are and how many there are. > # CLEANERS - 22 > # SHMVIRTSIZE - 1,400,000 > # SHMADD - 131,072 > # SHMTOTAL - 0 > # LRUS - 56 This should be the same as CLEANERS. How was this number determined? Your LRU queues are quite long. > # LRU_MAX_DIRTY - 5 > # LRU_MIN_DIRTY - 2 > # STACKSIZE - 32 > > I am considering changing to > > # Buffers - 2,000 You ARE going to do this on your last day, right? 2000 buffers for 600 users? I am missing something here. > # LRUS - 50 > # LRU_MAX_DIRTY - 60 > # LRU_MIN_DIRTY - 50 > # CLEANERS - 8 How long do checkpoints take at the moment? Perhaps you could supply more details, such as what problems do you have? What apps are you running, type of database usage? Is the system paging or swapping or IO bound, etc? Cheers, -- Mark. +----------------------------------------------------------+-----------+ | Mark D. Stock mailto:mdstock@mydas.freeserve.co.uk |//////// /| | http://www.informix.com http://www.informixhandbook.com |///// / //| | http://www.iiug.org +-----------------------------------+//// / ///| | |What year 2000 bug? year 2000 bug? |/// / ////| | |year 2000 bug? year 2000 bug? year |// / /////| | |2000 bug? year 2000 bug? year 1900 |/ ////////| +----------------------+-----------------------------------+-----------+