CPU Usage Alarm Threshold

CPU usage is monitored for all CPU and IO cards on the DSC - SP2000 Platform. These systems support three severity levels for the CPU usage alarms: Minor, Major, and Critical; one onset and one abatement threshold values are associated with each alarm severity. The thresholds can be set from 1 to 100% in the Web UI. There are no  initial values assigned to the threshold levels and the fields are clear by default (blank field). One or more of these severity based alarms can be disabled by clearing both onset and abatement thresholds levels.

A sysmon trap and syslog is generated EVERY time a CPU core crosses an alarm threshold level. The trap and log contain the Core Number, Percent Usage, Slot Number, and the severity of the alarm level that was crossed.

The CPU usage alarm control process ensures the following:

• previous alarms are cleared at system startup
  
  
• alarms are not created during the CPU startup
  
  
• alarms are raised as required in high CPU usage situations
  
  
• alarms are cleared when the CPU usage is below the set threshold
  
  
• alarms are logged in sysmon and slotmon

The following is recommended to configure the CPU usage alarm thresholds:

• CPU usage alarm thresholds need to be engineered to match the expected/normal levels that the system is likely to encounter. As with all multi-threaded computers, this depends on many factors, including traffic levels, background activities, and so on. It is recommended that the typical CPU usage levels experienced during high and low messaging traffic periods are analyzed in order to determine appropriate CPU usage threshold value.
  
  
• An alarm is disabled if the usage threshold levels are not assigned a value (fields are clear). If CPU usage levels require alarm threshold levels (minor, major, or critical), both the onset and abatement levels must be set as a pair. The onset threshold level must be greater than the abatement level. An alarm’s threshold levels must not overlap with other alarm threshold levels. The threshold levels must correlate to the alarm’s category (severity): Minor Alarm threshold levels < Major Alarm threshold levels < Critical Alarm threshold levels. Critical Alarms have the highest threshold levels and Minor Alarms have the lowest.
  
  
• Set threshold levels to a value that produces alarms when CPU usage reaches levels not considered normal (for example, beyond what is seen during peak traffic periods). If a certain threshold setting frequently gets triggered and investigation indicates that the system is operating normally and that the usage spike is due to normal system operations combined with traffic levels, then the threshold level should be raised.

To summarize, alarm usage threshold levels exhibit the following:

• Minor, Major, and Critical Alarm usage threshold levels are set in the Web UI.
  
  
• No initial values are assigned to threshold levels and are clear (blank field) by default.
  
  
• An alarm without onset and abatement threshold level values (fields are clear) is disabled.
  
  
• Onset and abatement threshold levels must be set in pairs.
  
  
• The onset threshold level must be greater than the abatement threshold level.
  
  
• Minor alarm threshold level < Major alarm threshold level < Critical alarm threshold level.
  
  
• An alarm’s usage threshold levels must not overlap with other alarm threshold levels.

To view the CPU Usage Threshold

1. From the Main Menu, click Processes.
   
   
2. Using the Process Details on drop-down list, select the CPU for which you want to see the CPU usage threshold.
   
   
3. Click Update.
   
   
4. Click CPU UsageThreshold.
   
5. Configure the CPU usage alarm as required.
   
   
6. Click Update.