Hi, trying to tune some of the performance issues on a HP box running Informix 7.3 UC3.
LRU's are set at 1 and 2 but the checkpoint are taking about 4-5 seconds on the average, and output of onstat -F shows that the system is doing most of the flushing at checkpoints, any Ideas on how to force it to do more LRU writes?
here are some of the values
the percent read cache is about 95 and write cache is about 80
I'm thinking about increasing the LRUS and the CLEANERS
Any suggestions on this?
System disk is being hammered pretty often, but that is probably because the database have not been reorganized in about 5 years and the high use tables have over 100 extents on them.
I think that the value of CLEANERS <= NUMAIOVPS.
I suggest him that reorganize all the base or the tables with more seven extents.
Another important theme is the layout of disks, if you use KAIO.
Please test output onstat -g iof, column "io/s".
Thank you Gustavo, that is exactly what I was thinking.
The database have not been reorganized in a while, they only have one dbspace spread out across 13 chunks some on the same disk some are not
and the tables and the extents are all over the place.
I'm going to monitor iof output for a day, see which chunks are being hit the hardest.