Configure HA Groups on BIG-IP

Posted in f5, big-ip, availability, load balance, application delivery, devcentral by psilva on April 25th, 2017

Last week we talked about how HA Groups work on BIG-IP and this week we’ll look at how to configure HA Groups in BIG-IP.

To recap, an HA group is a configuration object you create and assign to a traffic group for devices in a device group. An HA group defines health criteria for a resource (such as an application server pool) that the traffic group uses. With an HA group, the BIG-IP system can decide whether to keep a traffic group active on its current device or fail over the traffic group to another device when resources such as pool members fall below a certain level.

First, some prerequisites:

  • Basic Setup: Each BIG-IP (v13) is licensed, provisioned and configured to run BIG-IP LTM
  • HA Configuration: All BIG-IP devices are members of a sync-failover device group and synced
  • Each BIG-IP has a unique virtual server with a unique server pool assigned to it
  • All virtual addresses are associated with traffic-group-1

To the BIG-IP GUI!

First you go to System>High Availability>HA Group List>and then click the Create button.

hab1.jpg

 

The first thing is to name the group. Give it a detailed name to indicate the object group type, the device it pertains to and the traffic group it pertains to. In this case, we’ll call it ‘ha_group_deviceA_tg1.’

hab2.jpg

 

Next, we’ll click Add in the Pools area under Health Conditions and add the pool for BIG-IP A to the HA Group which we’ve already created. We then move on to the minimum member count. The minimum member count is members that need to be up for traffic-group-1 to remain active on BIG-IP A. In this case, we want 3 out of 4 members to be up. If that number falls below 3, the BIG-IP will automatically fail the traffic group over to another device in the device group.

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Next is HA Score and this is the sufficient threshold which is the number of up pool members you want to represent a full health score. In this case, we’ll choose 4. So if 4 pool members are up then it is considered to have a full health score. If fewer than 4 members are up, then this health score would be lower. We’ll give it a default weight of 10 since 10 represents the full HA score for BIG-IP A. We’re going to say that all 4 members need to be active in the group in order for BIG-IP to give BIG-IP A an HA score of 10. And we click Add.

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We’ll then see a summary of the health conditions we just specified including the minimum member count and sufficient member count. Then click Create HA Group.

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Next, we go to Device Management>Traffic Groups>and click on traffic-group-1.

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Now, we’ll associate this new HA Group with traffic-group-1. Go to the HA Group setting and select the new HA Group from the drop-down list. And then select the Failover Method to Device with the Best HA Score. Click Save.

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Now we do the same thing for BIG-IP B. So again, go to System>High Availability>HA Group List>and then click the Create button. Give it a special name, click Add in the Pools area and select the pool you’ve already created for BIG-IP B. Again, for our situation, we’ll specify a minimum of 3 members to be up if traffic-group-1 is active on BIG-IP B. This minimum number does not have to be the same as the other HA Group, but it is for this example. Again, a default weight of 10 in the HA Score for all pool members. Click Add and then Create HA Group for BIG-IP B.

hab82.jpg

 

And then, Device Management>Traffic Groups> and click traffic-group-1. Choose BIG-IP B’s HA Group and select the same Failover method as BIG-IP A – Based on HA Score. Click Save.

Lastly, you would create another HA Group on BIG-IP C as we’ve done on BIG-IP A and BIG-IP B. Once that happens, you’ll have the same set up as this:

ha2a.jpg

As you can see, BIG-IP A has lost another pool member causing traffic-group-1 to failover and the BIG-IP software has chosen BIG-IP C as the next active device to host the traffic group because BIG-IP C has the highest HA Score based on the health of its pool.

Thanks to our TechPubs group for the basis of this article and check out a video demo here.

ps