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Understanding Health Monitoring

Health monitoring is an SNMP feature that extends the RMON alarm infrastructure to provide monitoring for a predefined set of objects (such as file system usage, CPU usage, and memory usage), and for Junos OS processes.

You enable the health monitor feature using the health-monitor statement at the [edit snmp] hierarchy level. You can also configure health monitor parameters such as a falling threshold, rising threshold, and interval. If the value of a monitored object exceeds the rising or falling threshold, an alarm is triggered and an event may be logged.

The falling threshold is the lower threshold for the monitored object instance. The rising threshold is the upper threshold for the monitored object instance. Each threshold is expressed as a percentage of the maximum possible value. The interval represents the period of time, in seconds, over which the object instance is sampled and compared with the rising and falling thresholds.

Events are only generated when a threshold is first crossed in any one direction, rather than after each sample interval. For example, if a rising threshold alarm, along with its corresponding event, is raised, no more threshold crossing events occur until a corresponding falling alarm occurs.

System log entries for health monitor events have a corresponding HEALTHMONITOR tag and not a generic SNMPD_RMON_EVENTLOG tag. However, the health monitor sends generic RMON risingThreshold and fallingThreshold traps. You can use the show snmp health-monitor operational command to view information about health monitor alarms and logs.

When you configure the health monitor, monitoring information for certain object instances is available, as shown in Table 1.

Table 1: Monitored Object Instances

Object

Description

jnxHrStoragePercentUsed.1

Monitors the /dev/ad0s1a: file system on the switch. This is the root file system mounted on /.

jnxHrStoragePercentUsed.2

Monitors the /dev/ad0s1e: file system on the switch. This is the configuration file system mounted on /config.

jnxOperatingCPU (RE0)

Monitors CPU usage by the Routing Engine (RE0).

jnxOperatingBuffer (RE0)

Monitors the amount of memory available on the Routing Engine (RE0).

sysApplElmtRunCPU

Monitors the CPU usage for each Junos OS process (also called daemon). Multiple instances of the same process are monitored and indexed separately.

sysApplElmtRunMemory

Monitors the memory usage for each Junos OS process. Multiple instances of the same process are monitored and indexed separately.

 

Related Documentation

 

Published: 2014-07-23

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