Troubleshooting an Unexpected Failover in HA- High Availability

03/26/2020 33 5290

DESCRIPTION:

This article will define the steps you can take to prevent or resolve an issue with unexpected failover either on your own or with the help of SonicWall support

RESOLUTION:

The first step is to gather data from both units. Since a failover can happen for more than one reason the logs from both units are required to help determine the root cause.  If you are planning on the help of support to determine the cause all of the following files must be uploaded to your service request. Follow this link on how to gather the required files:

How to gather required files for SonicWall Support

Pro tip - Create your case online before calling into support, you will be routed directly to your support queue bypassing customer service and significantly reduce your time on the phone:

How to submit a support case online at MySonicWall.com

  1. Download the 'All' tracelog file

  2. Search for the HA event using MM/DD format

  3. Once you find the event you can use these clues to determine next steps. Here in the primary's tracelogs we see the standby unit was active, the primary unit stopped recieving heartbeats from secondary. The secondary unit triggered an outage so the primary became active. Now we need to check the secondary logs, tracelogs, the configuration including physical configuration for any other issues on this date that may have contributed to this event:

Some common reasons for an unexpected failover are:

1. HA Misconfiguration- It's important to have HA set up correctly to ensure stability. Follow the tips in this KB for HA best practices and be sure you have your X0 monitoring IPs configured. The X0 functions as a backup HA link when there is a connection between the primary and standby X0 interface.

Tips for High Availability Best Practices

  2. Unsupported SFP modules:

SFP and SFP+ modules that can be used with SonicWall firewalls

  3. System Crash- Check the uptime of both active and standby units in System Status to determine if either one has gone down recently:

Troubleshooting a System Crash