How can I diagnose fence_ilo failures when connecting to an iLO version 1 or 2 device in RHEL 5, 6?

Solution Verified - Updated -


  • Red Hat Enterprise Linux (RHEL) 5 or 6 with the High Availability Add On
  • HP servers with iLO version 1 or 2


  • Are there steps that can be followed to diagnose what is causing fence_ilo to fail?
  • How to use 'fence_ilo' to troubleshoot fence issue of iLO fence agent?


See the Diagnostic Steps below for ways to troubleshoot failed fence_ilo operations. Some common items to check are:

  • Ensure you are using the appropriate fence agent: fence_ilo for iLO 1 or 2, fence_ipmilan for iLO 3 or 4
  • Ensure that telnet functionality is enabled in the iLO management settings
  • If SSL connections are required, make sure to configure the fencedevice with ssl="on" in /etc/cluster/cluster.conf, or -z on the commandline
  • If using ssl="on" or -z, make sure SSL connections are enabled in the iLO settings
  • Ensure no firewalls are blocking access to port 23 (telnet) or port 443 (telnet_ssl)
  • Ensure the power_wait setting is not too low
  • Ensure the fence device delay is not causing failures
  • A power regulator in some hardware could interfere with iLO power off commands. HP BL495c gen5 has been validated as a potentially affected model.

Diagnostic Steps

  • Try running the command manually from the command line to check the status (-z is optional, depending on whether SSL functionality is enabled in the iLO. If it is, communication will go over port 443 for telnet_ssl)
# fence_ilo -a <iLO IP/Hostname> -l <username> -p <password> -o status -v [-z]
# fence_ilo -a -l admin -p mypassword -o status -v -z
  • Try manually telnetting to the iLO to see if a connection can be made:
# telnet <iLO IP/Hostname> 23
# telnet 23

If a connection cannot be made, check the firewall settings, IP/hostname, and network connectivity. If telnet connects successfully, try pasting the following line into the connection and see if XML data is returned:

<?xml version=\"1.0\"?>\r\n
  • If SSL is enabled, try telneting to the iLO using telnet_ssl
# /usr/lib/fence/telnet_ssl <iLO IP/hostname> 443
# /usr/lib/fence/telnet_ssl 443

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