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newf5learner_13
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Aug 05, 2016

F5 LTM hardware failover Vs network Failover

I have been looking for best practices of configuring HA across the LTMs and I have few questions.

 

  1. Does the Hardware failover (DB9 -serial cables connected) method is still supported in versions 11.X and 12.X ?

     

  2. If I have both Serial failover cable and standard network failover via interface configured, which one will take the preference?

     

thanks

 

  • One more quick one.. Usually to check the HA status we used to issue command 'b ha status show' == 'tmsh show sys ha-status all-properties'

    How can we know more details if we have Hardware failover cable connected between the LTMs running on version 11.X or 12.X ? The output of 'tmsh show sys ha-status all-properties' gives us any information?

    (f5l1)(cfg-sync)(Active)(/Common)(tmos) show /sys ha-status all-properties | grep hardware
    hardware-failover     sod           go-active                     no    yes      no    0       sod           0
    
  • The DB9 hardware fail over is still supported. When you enable network fail over you are disabling the hardware fail over.

     

  • i believe this SOL explains most of the things you want to know

     

    http://support.f5.com/kb/en-us/solutions/public/2000/300/sol2397.html

     

    F5 advise to configure both, if you are planning on hardware failover that is, mainly for the reporting. but that also shows that configuring network failover does not disable hardware failover.

     

  • thanks for your answers. :)

     

    How can we know more details if we have Hardware failover cable connected between the LTMs running on version 11.X or 12.X ? The output of 'tmsh show sys ha-status all-properties' gives us any information?

     

    Answer posted by experts 'tmsh show sys failover cable' tired that on a live device. It worked.

     

  • @Mike, From where did you get the information in regards to which failover method has precedence? That's actually the opposite. https://support.f5.com/kb/en-us/solutions/public/2000/300/sol2397.html

     

    (My point of view) When you configure HA, it's best to never use the hardwired failover, and only stick to network failover. F5 recommends to configure both, but I think that having a superior HA solution suppressed by something based on very low-level voltage heartbeats does no good to reliability.