Monitoring CPU Usage on a WSA Appliance Using SNMP

Question

How should I monitor CPU usage on my WSA appliance deployment using SNMP?

Environment

Any WSA appliance deployment

Solution

Part of monitoring the health of a WSA deployment is monitoring CPU usage. CPU usage is exposed via SNMP for ease of monitoring.

The relevant portion of the SNMP MIB is named cacheBusyCPUPct, with an OID of .1.3.6.1.4.1.15497.1.2.3.1.5.0. Polling this OID results in an integer value between 0 and 10,000, expressed in hundredths of a percent. For instance, a value of 347 indicates CPU usage of 3.47%.

CPU usage is defined as percentage of available CPU on the device used by all processes in the last ten seconds. This includes:

• OS kernel
• Main HTTP proxy process
• Anti-malware scanning engines
• URL categorization and WBRS engines
• Logging and reporting
• Web UI and CLI
• Other miscellaneous processes

This value should be similar to the values exposed in the web UI in the Overview report, and in the CLI by the "rate" command. Differences should be slight, and indicate slight differences in sampling time between the three locations.