How To Prevent "Can't open file", "Too many open files" or Similar Errors from Interrupting Zenoss Services

Applies To

  • Zenoss Resource Manager  (all versions)
  • Analytics and Optimization (all versions)
  • Service Impact (all versions)


Both the Linux operating system and certain applications such as the Zends database may have limits on the number of files / file descriptors that can be simultaneously open. If these limits are exceeded on a system hosting Zenoss, Zenoss can stop functioning correctly.


When the Linux file system limit is exceeded, Zenoss or some of its dependencies may stop working correctly. When this occurs, the following phrase may appear in the Linux syslog or in Zenoss logs:

Too many open files


  1. Log onto the Zenoss host.
  2. Change to the zenoss user:

    # su - zenoss

  3. Identify the current open files limit for the zenoss user:

    $ ulimit -n

    If this value is low (such as a common default value of 1,024 for some Linux distributions) perform the following to increase the file limit:

    1. change back to the root user:

      $ exit

    2. Depending on your system, make the following changes:
      1. If your system is running Resource Manager, add the following lines to the /etc/security/limits.conf file:
        zenoss soft nofile 4096
        zenoss hard nofile 10240
      2. If your system is running Analytics and Optimization, add the following lines to the /etc/security/limits.conf file:
        root soft nofile 999999
        root hard nofile 999999
        zenoss soft nofile 999999
        zenoss hard nofile 999999
      3. If your system is running Zenoss Service Impact 4.2.6 or later, add the following lines to the /etc/security/limits.conf file:
        zenossimpact soft nofile 999999
        zenossimpact hard nofile 999999
    3. Save and Exit the file(s).
    • Repeat steps 2-3 above to verify that the changes have taken affect.
    • Restart Zenoss:

      $ zenoss restart

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