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jkramer9's avatar
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Sep 23, 2020

GTM/LTM Monitors

Hi everyone,


I have an interesting scenario with some questions.


Wide IP - 1 Pool - 2 Pool Members

The Pool Members are on LTMs (DC1 and DC2)


The LTM Pools have custom health check monitors in place, and the servers in DC1 and DC2 are passing those health check monitors and are green on the LTMs.


The GTM Pool also has a custom health check monitor defined. The odd behavior which I'm seeing though, is that DC1 Pool Member is Green (Online), while the DC2 Pool Member is Red (Offline). I can't seem to find out an explanation as to why. The GTM Pools health check is checking a particular file for a matching string. Both servers have the same exact file in their root directory, so in such a case, both should be either Online or Offline. I checked the health check file and technically, both should be failing the health check...I'm not entirely sure how the DC1 member is green. Any advice to tshoot this further and get to the bottom of it?


Secondly, in a design scenario like the above, typically, I would only set up the health check monitors at the LTM level if there is only one GTM pool. My understanding is that the status of those LTMs would be communicated via iquery in between the LTM/GTM and those pool members would fail/recover according to the status of the LTMs. Wouldn't this be the leanest and simplest approach? If a GTM only has 1 pool, is there an actual need or point in configuring a health check monitor at the pool level? Wouldn't GTM Pool level health monitors only make sense when more than one pool is tied to a single FQDN? Why would this be set up in such a way and how does this benefit the design and deployment?





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