Re: Parameters LRU_MAX_DIRTY & LRU_MIN_DIRTY - UNIX

From: "John (Jack) O'Hara" <johara@writeme.com> > >Our Informix Dynamic Server 7.22 running on Sun Solaris comes to a crawl >when usage reaches high levels. However, I've noticed that "SELECTS" >continue to be quick while UPDATES and INSERTS can take from 20 to 60 >seconds each. I noticed that our DBA has the LRU_MAX_DIRTY parameter >set to 2% and LRU_MIN_DIRTY set to 1% while Informix recommends defaults >as high as 60% and 50% respectively. The DBA insists this is not our >problem and refuses to even change these values a little. I'm inclined to agree with him. >Has anyone had experience tuning these values? Am I correct to believe Yes. >that these values are forcing such a high rate of flushing dirty buffers >to disk that this unnecessary I/O is impacting UPDATES and INSERTS which >create dirty pages? No. The buffer flushing is *not* unnecessary. I would rather look at things like over indexing, triggers and stored procedures. At the engine level, I would look at increasing the number of LRU queues and cleaners, possibly implementing a fragmemtation strategy. I'm sure the more intelligent among us will offer some more useful advice. Such a clear dichotomy in behaviour leads me to suspect that the problem may be something which only relates to updates and deletes, such as a set of poorly written triggers or stored procedures. You can go and sharpen your hair now. :-) ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com