ITM Agent Insights: Limitations to monitoring a Symbolic Link versus File using the Linux OS agent

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If you have a symbolic link defined which points to a monitored log, however the updates you expect to see for "File Changes" are not reflected in the situation you have defined. Why does this occur. Are there limitations to monitoring a symbolic link? The following attributes are used "Path", "Link Name" and "Last Changed Time" attributes from File Information attribute group for the Linux operating system agent.

No alerts received for a situation setup with "Path", "Link Name" and "Last Accessed Time" attributes from File Information attribute group, even though the monitored log gets updated. The root cause is the incorrect situation definition. Any situation created in IBM Tivoli Monitoring (ITM) needs to be verified as follows, in the example below:

1) Any situation setup in ITM needs a review of attribute value shown in TEPS. 

2) In the example below we will see the attribute values from the console and compare them to the ones shown in TEP client. SLtest.log is the symbolic link pointing to /opt/IBM//ITM/test.log

• Console display for SLtest.log

• TEP client display for SLtest.log

• Console display for the actual test.log

• TEP client display for the actual test.log

3) Comparing the two you can see the "Last Changed Time" for the SLtest.log and actual test.log are different. So the situation setup to monitor the actual test.log using the symbolic link will cause a conflict.

4) Defining a situation to monitor the actual log "test.log" with "Path", "File" and "Last Changed Time" attributes from File Information attribute group will work to capture exactly when the test.log was last updated.

NOTE: Please note that if the symbolic link statistics are updated as per your requirements you can use the symbolic link for with "Link Name" attribute as well. You need to ensure that is happening though by reviewing the attribute values in the TEP client.

Defining a situation to monitor the actual log "test.log" with "Path", "File" and "Last Changed Time" attributes from File Information attribute group will resolve the issue.

Additional ITM Agent Insights series of IBM Tivoli Monitoring Agent blogs are indexed under ITM Agent Insights: Introduction.

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