Re: LRU writes

brian, > > response time, that is pretty much the end goal. > > Our response times suck! first of all, have you migrated from another version, where you have something to compare it with? that is an important point. the next question is, have you run update statistics on your databases, (especially if this was a migration)? when i did my migration, i forgot to run update statistics on the last batch of databases. queries that were taking less than one minute on the old system, were now taking 15-20 minutes, even more, and slowing the system to a crawl. after i ran update statistics (high, my databases are not that big) the queries wereeven faster than on my old 5.01 system. that is the first question, no sense in doing anything else if this hasn't been done. > Our % read cache is 99.9x% and writes are 98.x We have 10240 buffers then you have enough buffers. > distributed in 20 LRUs. LRUMIN is 5, LRUMAX is 10. Would it make sense to > increase the number of LRUS, thus having more queues to spread the > buffering across? Or does queue management start to become an issue. > Checkpoints, every 30 minutes, are 10 secs. queue management does become an issue. for the number of buffers that you have, you don't need any more. i have 16000 buffers, and 10 queues. how about the number of CLEANERS? usually it's said that they should equal the number of devices that you have, but i usually go with the same number of LRU queues, so there is one cleaner per queue. it doesn't necessarily sound like this is the source of your problem. the performance problem that relates to this is when every X minutes, the system freezes for Y seconds while it does a checkpoint, and so users sit there with their application frozen for those Y seconds. that might not be tolerable, so you tune the above scenario so that the checkpoint takes much less time to complete, and so is not noticable, or as noticable. to seconds every 30 minutes sounds resonable to me. let me know about the statistics, and we can try to go from there if this doesn't do it. > > B. > > ------------------------------------------------------------------------- > |Brian P. Hampson Internet : brian@asl-labs.bc.ca | > |System Administrator, Air(2m/70cm): VE7NNW | > |Analytical Service Labs Fidonet : Brian Hampson 1:153/733| > |Vancouver, BC | > |+604-253-4188 | > | Specialists in Environmental Chemistry | > | | > ------------------http://www.asl-labs.bc.ca/----------------------------- > > >