size buffers

georgipa · #1 (**permalink**) 12-24-02, 07:22

hi,

please I need to calculate the size of buffers, who have help me.

thank you.

Georgi

Roelwe · #2 (**permalink**) 12-31-02, 05:43

What buffers do you want to calculate?

onstat -g seg
will display an overview of the main memory segments.

onstat -g mem
displays the memory size per pool.

georgipa · #3 (**permalink**) 12-31-02, 10:36

Quote:

Originally posted by Roelwe
What buffers do you want to calculate?

onstat -g seg
will display an overview of the main memory segments.

onstat -g mem
displays the memory size per pool.

I need to calculate el value of buffers of file onconfig.std

Thank you.

tlohan · #4 (**permalink**) 01-02-03, 12:45

Hi,

A formula for calculating BUFFERS is:

Buffers = (RAW_BUFFERS/LRU_MIN_DIRTY)*100,

where:

RAW_BUFFERS = ((NUMBER_OF_DAYS * (NUMBER_OF_ROWS (for a day) * PAGES_FOR_TABLES))

Informix recommend NUMBER_OF_DAYS be set to 2.

Hope this helps.

Roelwe · #5 (**permalink**) 01-06-03, 09:06

I always use trial and error. The most important thing is to keep the checkpoint duration as small as possible.
If you have a big chunk of memory available in your system, bring up the BUFFERS parameter and fine-tune with LRU/CLEANERS/LRU_MIN_DIRTY/LRU_MAX_DIRTY.
Make sure that your checkpoint duration stays low.
Be aware that not only the BUFFERS parameter affects the total amount of memory allocated by the informix server.