You can obtain statistics that relate to buffer availability as well as information on the buffers in each LRU queue.
The statistical information includes the number of times that the database server attempted to exceed the maximum number of buffers and the number of writes to disk (categorized by the event that caused the buffers to flush). These statistics help you determine if the number of buffers is appropriate. For information on tuning database server buffers, see your IBM Informix Dynamic Server Performance Guide.
Information on the buffers in each LRU queue consists of the length of the queue and the percentage of the buffers in the queue that have been modified.
You can use the onstat utility to obtain information on buffer-pool activity. You also can execute onstat options from ISA.
For more information about the onstat options, see information on the onstat utility in the IBM Informix Dynamic Server Administrator's Reference.
The onstat -p output contains a statistic (ovbuff) that indicates the number of times the database server attempted to exceed the maximum number of shared buffers specified by buffers value in the BUFFERPOOL configuration parameter.
Execute onstat -F to obtain a count by write type of the writes performed. (For an explanation of the different write types, see Describing Flushing Activity.
The onstat -F command displays totals for the following write types:
The onstat -F command also lists the following information about the page cleaners:
For an example of onstat -F output, see information on the onstat utility in the IBM Informix Administrator's Reference.
Execute onstat -R to obtain information about the number of buffers in each LRU queue and the number and percentage of the buffers that are modified or free.
For an example of onstat -R output, see information on the onstat utility in the IBM Informix Administrator's Reference
Query the sysprofile table to obtain the statistics on write types that are held in the following rows.