Re: Performance Problems with 7.30.UC7XB

Dominic Binks wrote in message <3778E4C9.47335C3D@aethos.co.uk>... >Doug Agnew wrote: >> >> Running Informix 7.30.UC7XB (for SAP) on >> HP-UX 10.20 -- machine is T520 w/4 processors and 1.75 Gb memory. EMC >> Symmetrix with HP-PB Fast/Wide SCSI connections. >> >> Experiencing cache-hit read % of < 80% (and needless to say, our users are >> screaming) >> > >I'm assuming this is a circumstance that has just arisen (and looking at >the onconfig) I'm also assuming you may have upgrade recently? > >We are experiencing a similar problem. Try onstat -P and see how many >pages of your cache are being used for btree vs. data. This appears to >be a "feature" of 7.30 that is difficult to reproduce in test >situations. If this is the case, you may wish to raise an issue with >Informix tech support. > >Dominic > >-- >Dominic Binks/Systems Engineer/Logica-Aldiscon >400 Park Avenue/Aztec West/Bristol/BS32 4TR/United Kingdom >Tel: +44 1454 614455/Fax: +44 1454 620527/Mobile: +44 498 693964 >E-mail: dominic.binks@aethos.co.uk We found one error, that the KEYFIRST environment variable should NOT have been set. We rebooted our system and 'SO FAR', things are performing well. The proof of the pudding will be in about 12 hours when things have traditionally degraded. As for onstat -P, yes, we had noticed the 'feature' that 7.3 provided. In discussion with Art Kagel, it appears that this happens because the data is considered 'low priority' buffer pages while index buffers are 'med-high'. And, when looking for a buffer to swap, Informix prefers to replace low with low, hence the index buffers almost never get flushed. Don't know what can be done about it, until Informix changes its algorithms..... Doug