Re: Buffer Waits Ratio
On Wed, 8 Dec 1999, Henderson, Scott wrote: > Friends, > > > Informix Version: 7.30 FC7 > OS: HPUX 11.0 > Hardware: HP9000 Series 800 V2500 > Disk Array: EMC 3700 > Application: OLTP (strictly database server) > Misc. 16 CPU, 8GB mem, 2 instances > > > I've been making use of the bufwait ratio formula [ratio = (bufwaits / > (pagreads + bufwrits)) * 100] on my production servers. During normal day > to day usage it hovers at around 15%. I know the ideal target is 10%. > During heavy activity in the afternoon I have seen measurements of >25%. I > plan to increase BUFFERS,LRUS and CLEANERS and maybe NUMCPUVPS. I would > appreciate if you guys/gals confirm my plan and also have a look at my > onconfig file and recommend any improvements. > > Informix recommends 4 LRUS per NUMCPUVPS (Admin Guide Vol2 33-45) > I have 6 CPUVPS, 28 LRUS (whoops) looking after 100000 BUFFERS, each LRU is > looking after approximately 7000 pages. We had 4 LRUS for 3 NUMCPUVPS and a buffer wait ratio (aka KBR for those who know it by another name) > 25%. I increased the number of LRUS to 16 and the ratio remained > 25%. After increasing LRUS to 30 I got the ratio down to 7% and it has been hovering there ever since. We have 60,000 buffers or 2000 per LRU. Hope this helps. ==================================================================== Harold Luse Phone: (970) 491-4120 Veterinary Teaching Hospital Fax: (970) 491-4123 Colorado State University Pager: (970) 229-8173 Fort Collins, Colorado USA E-mail: hluse@vth.colostate.edu ====================================================================
In article <82mqij$ibf$1@news.xmission.com>, Luse Harold <hluse@vth.colostate.edu> writes >We had 4 LRUS for 3 NUMCPUVPS and a buffer wait ratio (aka KBR for those >who know it by another name) > 25%. I increased the number of LRUS to 16 >and the ratio remained > 25%. After increasing LRUS to 30 I got the ratio >down to 7% and it has been hovering there ever since. We have 60,000 >buffers or 2000 per LRU. Hope this helps. > We run 1/2 CPUS, 8 LRUs, LRU_MIN/MAX 5/10 and 10,000 BUFFERS bufwaits <3% (Even seen 0.1%!!) >==================================================================== >Harold Luse Phone: (970) 491-4120 >Veterinary Teaching Hospital Fax: (970) 491-4123 >Colorado State University Pager: (970) 229-8173 >Fort Collins, Colorado USA E-mail: hluse@vth.colostate.edu >==================================================================== > -- David Williams