Re: Performance problem after merging db server

Posted in 1998

Greg Moye — Wed, 05 Aug 1998 11:01:22 -0500 — source: Informix-list mailing list archive (1991-1998)

Stephan Stresing wrote: > > Hi, > we have a heavy performance problem after 'merging' two db systems > to one. We did this because according to the Informix Performance guide > and the advices of Informix experts. The most obvious thing is that BUFFERS 5000 is *WAY* too low. Assuming you have one instance with 2 databases, I'd bump it to 65536, bounce the engine, and watch your read hit ratio (it should improve dramatically). This may require the kernel parameter SHMMAX to be bumped, if so have it set to 4 GB and forget about it. I'd also set RA_PAGES to 32, RA_THRESHOLD to 30 and LRU's to 127 Brace yourself for some screaming performance....enjoy. Greg p.s. if you have 2 instances, one database apiece, cut my BUFFERS suggestion by as much as half. Also, make sure your statistics are current, it's so easy to forget after a migration. Poor / nonexistant stats will produce indescribably bad performance.