Forum Discussion

Steven_J__Willi's avatar
Steven_J__Willi
Icon for Nimbostratus rankNimbostratus
Apr 27, 2014

Priority Group Activation, why use it?

If you have 3 members that are active within a pool and you select round robin LB method and set the priority group activation for less than 2, the virtual server is only going to use two of three no...
application delivery
LTM
management
performance
Kevin_Stewart's avatar
Kevin_Stewart
Icon for Employee rankEmployee
Apr 27, 2014

If I may add, ratio and priority group are different things. If all or some of the members of a pool have the same priority, then any ratio differences will be applied. If a pool member is in a higher priority group than other members, then ONLY that pool member will be selected, until the PGA threshold is met. So for example:

1.1.1.1    Ratio 1    PG 4
1.1.1.2    Ratio 2    PG 3
1.1.1.3    Ratio 1    PG 3
1.1.1.4    Ratio 1    PG 2
1.1.1.5    Ratio 1    PG 1
1.1.1.6    Ratio 1    PG 1

As long as the PGA threshold for PG 4 is not met, only that member will be used. Once it fails, as long as the PGA threshold for PG 3 is not met, only members in the PG 3 group will be used. They will, however, use a 2:1 ratio for load balancing. Members in PG 2 and 1 won't get used until the higher level groups are exhausted respectively.