Re: KAIO vps, and bufwaits

Neil, Dont forget that BUFFWAITS do not always mean you dont have enough buiffers. If one thread A wants a record stored in buffer X but thread B is updating a record that is also in buffer X, thread A gets a BUFFWAIT. Jason On Fri, 06 Feb 1998 22:03:42 +0000, Neil Truby <ntruby@netcomuk.co.uk> wrote: >I've recently moved a poorly-performing database server from a Sun Sparc >20 to a Sun E4002 with 1.5 GBytes of memory, and 2 processors. It's >running superbly now, but I'm still keen to know where my bottlenecks >are. > >onstat -g ioq consistently shows my kio VP with a maxlength of 16,>suggesting that the system is I/O bound. In a sample output of onstat >-g ioq in "Informix Unleashed", three kio VPs are shown, but no >explanation is given on how to configure a system to use this many (if >in fact you can). > >Does anyone know how to set up extra KAIO vps? > >Also, despite having 200M of BUFFERS, onstat -p is still showing some >bufwaits. The read cache rate is above 99%, but the write remains >around 87% - the same as on the Sparc when BUFFERS was set to 50M. The >new system isn't swapping and hardly pages; do the bufwaits suggest a >further increase in BUFFERS is warranted? > >Thanks > >Neil Truby >Chase Manhattan Bank >Bournemouth, UK >neil.truby@chase.com