Monitoring the Shared-Memory Profile and Latches

Monitor the database server profile to analyze performance and the use of shared-memory resources. The Profile screen maintains cumulative statistics on shared-memory use. To reset these statistics to zero, use the onstat -z option. For a description of all the fields that onstat displays, see information on the onstat utility in the IBM Informix Dynamic Server Administrator's Reference.

You can obtain statistics on latch use and information on specific latches. These statistics provide a measure of the system activity.

Using Command-Line Utilities

You can use the following command-line utilities to monitor shared memory and latches:

• onstat -s
• onstat -p

onstat -s

Use onstat -s command to obtain latch information.

onstat -p

Execute onstat -p to display statistics on database server activity and waiting latches (in the lchwaits field). For an example of onstat -p output, see information on the onstat utility in the IBM Informix Administrator's Reference.

Using IBM Informix Server Administrator

You can use ISA to obtain information about latches, spin locks, and profiles.

Using ON-Monitor (UNIX)

Select Status > Profile. The screen displays shared-memory statistics, as well as the current operating mode, the boot time, the current time, and latches.

Using SMI Tables

Query the sysprofile table to obtain shared-memory statistics. This table contains all of the statistics available in onstat -p output except the ovbuff, usercpu, and syscpu statistics.