Re: How do I .... ?

1689@MN.LAWSON.lawson.com (Anjan Chakraborty) writes: >I am getting very high chunk writes and almost 0 LRU writes against onstat > -F >and >high duration against onstat -m. >How do I solve this problem ? >I have CKPTINTVAL=300,NUMAIOVPS=20,CLEANERS=6,LRU_MAX_WRITE=20, >LRU_MIN_WRITE=10,LRUS=8,BUFFERS=60000,PHYSFILE=60000, >MULTIPROCESSOR=1,NUMCPUVPS=1,SINGLE_CPU_VP=0,RESIDENT=1 >36 Logical log files,LOGSIZE=4000, information in 6 disks and HP-UX 10 with >512 M memory/2 processors and running ontape -c. >If anybody has some suggestions, I will really appreciate that. >Thanks. >Sincerely, >Anjan >e-mail:anjan.chakraborty.lawson.com Anjan, We had a very similar situation after we installed. We are still in the process of tuning, but we have improved our LRU writes dramatically. Through the process of trial and error we have slowly decreased our BUFFERS from 50000 to 16000. We also dropped LRU_MAX_WRITE to 10 and LRU_MIN_ WRITE to 5. As we decreased the buffer size we say the ratio of LRU/CHUNK change from 1/10 to about 3/2. We also decreased our checkpoint time from 7-8 seconds to 2 seconds. When we ran onstat -F at 15 second intervals between checkpoints we found that we never had enough dirty buffers to start the page cleaners working. By shrinking the number of buffers AND the percentage of them allowed to be dirty we forced the page cleaners to do much more work between checkpoints. We are still looking at ways to cut the checkpoints to an average of 1 second. As we have shrunk the BUFFERS we finally hit the point where we started doing FG writes and stopped. We have 8 LRU_QUEUES and 8 PAGE_ CLEANERS. We have contemplated adding more PAGE_CLEANERS, but our research is unclear whether this would help. My advice is to adjust your parameters slowly, watch performance carefully and see what happens. I also recommend the book "INFORMIX-ONLINE PERFORMANCE TUNING" by Elizabeth Suto. Good Luck! Dave Thacker Omni Hotels Reservation Center