Uploaded image for project: 'OpenNMS'
  1. OpenNMS
  2. NMS-5085

Default hrStorageUsed disk space relativeChange threshold only alerts on a sudden _increase of free space_, not a decrease of free space

    XMLWordPrintable

    Details

    • Type: Enhancement
    • Status: Closed (View Workflow)
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 1.8.16
    • Fix Version/s: 15.0.0
    • Component/s: Thresholding
    • Security Level: Default (Default Security Scheme)
    • Labels:
      None

      Description

      The default rate-of-change threshold alert in thresholds.xml as of OpenNMS 1.8.16 only alerts on a sudden increase of free space:

      <group name="hrstorage" rrdRepository="/var/lib/opennms/rrd/snmp/">
      ...
      <expression type="relativeChange" ds-type="hrStorageIndex"
      value="0.5" rearm="0.0" trigger="2"
      ds-label="hrStorageDescr" filterOperator="or" expression="hrStorageUsed / hrStorageSize * 100.0">
      <resource-filter field="hrStorageType">^\.1\.3\.6\.1\.2\.1\.25\.2\.1\.4$</resource-filter>
      </expression>
      </group>

      As per http://www.opennms.org/wiki/Thresholding , the value of 0.5 triggers on a 50% relative change drop in the measured value, which is the percentage of storage used. A drop in this value indicates more free space has suddenly become available.

      Having more free space is not generally an alert condition but less free space is, thus adding the following threshold would be a helpful enhancement. The trigger is changed to 1 as well, as this is the actual behavior (the attribute is currently unused per the wiki documentation).

      <expression
      description="Trigger a warning event when the percentage of disk space used on any disk of type hrStorageFixedDisk (e.g. a locally attached or USB-attached hard disk) increases by a relative 33.3% compared to its most recent previous measurement (e.g. there is suddenly less free space)"
      type="relativeChange" ds-type="hrStorageIndex"
      value="1.333" rearm="0.0" trigger="1"
      ds-label="hrStorageDescr" filterOperator="or" expression="hrStorageUsed / hrStorageSize * 100.0">
      <resource-filter field="hrStorageType">^\.1\.3\.6\.1\.2\.1\.25\.2\.1\.4$</resource-filter>
      </expression>

      I tested this with OpenNMS 1.8.16 by copying a file to a drive that increased its space used from 47% used to 64% used and got the following alert as expected:

      Relative change exceeded for SNMP datasource hrStorageUsed / hrStorageSize * 100.0 on interface 10.1.1.8, parms: label="E:\ Label:Data2 (SSD physical drive) Serial Number 602c3eb8" ds="hrStorageUsed / hrStorageSize * 100.0" value="63.67" instance="3" previousValue="47.54" multiplier="1.333"

      Regards,
      Tim Miller Dyck

        Attachments

          Activity

            People

            • Assignee:
              indigo Ronny Trommer
              Reporter:
              tim@peaceworks.ca Tim Miller Dyck (work)
            • Votes:
              1 Vote for this issue
              Watchers:
              3 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved:

                Time Tracking

                Estimated:
                Original Estimate - 30 minutes
                30m
                Remaining:
                Remaining Estimate - 30 minutes
                30m
                Logged:
                Time Spent - Not Specified
                Not Specified