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Active standby pool members

I'm currently using Priority Group Activation method to accomplish my first objective and it's been working great. However, I have more requirements than just active standby real servers. The situation gets complicated when my primary server fails and later comes back online. When it fails, there is no question about it, all requests will hit the standby server. Here's a tricky part when the primary comes back online. Because of the Priority Group Activation that I have above, when the primary comes back, all traffic would go back to the primary. This is NOT what I want. My new requirement is that when the primary comes back, I still want my traffic to hit the standby unless I want to manually force the standby offline. Some people in this forum have suggested to use Destination Address Affinity in combination with Priority Group Activation. Now before I go into details, I wanted to be clear on my objectives.

  1. Primary and standby, all traffic goes to primary
  2. Important: ssh traffic, I don't want my connections to be closed or reset when failover occurs
  3. When primary fails then later comes back, I want my traffic (new and existing) stays on the standby until I manually take the standby offline.
  4. When both nodes are online (important, especially after the primary is recovered from a failure), I don't want requests to hit both servers due to Priority Group Activation and destination Address Affinity combination.

How do I achieve all of those objectives above? Please advise.

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Answers to this Question


Enable manual resume on your health monitor.
And change (under advanced configuration) your pool response to load balancing fail to reselect.



Comments on this Answer
Comment made 20-Nov-2017 by k20 66

I don't want to manually re-enable the node. I know it's an option. However, this option doesn't appear to be the best option.

As for your second suggestion, that's how it is currently being configured today.

Comment made 20-Nov-2017 by BigD 281

Quoting what you said: "I still want my traffic to hit the standby unless I want to manually force the standby offline."

How is that different form manual enabling the primary?

Comment made 20-Nov-2017 by k20 66

Good question. The difference is who is going to manually do it. The server guy or the F5 admin. In our case, the server guy wants the control. That's why that option is not the best option.

Comment made 21-Nov-2017 by BigD 281

Ah, that makes more sense.


The solution is iCall

You can use alertd to create a trigger when a pool member in your pool gets marked down.
This triggers a tcl script that swaps the priority group activation settings for the pool members.

iCall has a few documents and examples, so have a look.