Re: BUFFERS setting

Neil Truby <ntruby@netcomuk.co.uk> wrote in article <32B85E13.1779@netcomuk.co.uk>... > I'm running OnLine 7.13 on a Sun Sparcserver 20. It has 160M of physical > memory. We have a bought-in application which is very resource hungry. > At the suggestion of Tech Support I bumped BUFFERS up to 20K > (40MBytes). However, onstat -b consistently shows only a few hundred of > the 20,000 BUFFERS modified at any one time. Am I correct in inferring > that I therefore have BUFFERS too high, and could begin to reduce it > until I notice degradation in my read/write cache percentages (currently > 93 and 87 respectively)? The number of buffers modified just tells you how many of the cached pages have been modified since the last checkpoint. You're still getting a tremendous benefit on reads. According to the statistics you reports, 93% of reads came from the buffers, not requiring a physical read. The perecentages you are observing (93 and 87) are actually a bit low, but depending on your application you might not do any better. Hit rates of 98+ (read) and 90+ (write) are farily common in many of the installations I've seen. I certainly wouldn't lower the number of buffers. In fact, adding more physical RAM and increasing buffers MIGHT help improve the hit rates. -- Irwin Goldstein Objective Software Systems, Inc. http://www.objectsoft.com