Forum Discussion
Peter_Z
Cirrus
CirrusMember ratio & dynamic LB alogithms
Hi,
I'm new to F5 and trying to figure out, how the dynamic LB algorithms and member ratio go together when they are both set. For example, let's say I have following configuration:
LB method: Least Connections
Member Ratio Connections Status
member A 1 2 up
member B 3 4 up
member C 3 12 up
What is the first value that the big-ip looks for? Is it the number of active connections and the ratio is considered only when two ore more members have the same number of connections? How will the next four connections be distributed?
How will that change, if priorities are set as follows:
LB method: Least Connections
PG activation: Less than 2
Member Ratio Prirority Connections Status
member A 1 1 2 up
member B 3 3 4 up
member C 3 3 12 up
In case all members are up and priority group activation is set to 'less than 2', will memberA be ever used in loadbalancing?
Thanks
1 Reply
Cspillane_18296Nimbostratus
Hello Peter,
I'm not sure if I'm missing something here but I don't think you can use Ratio (member) and Least Connections together, they're set across the pool as a load balancing method and are therefore mutually exclusive. Do correct me if I've missed something!
Ratio is normally used when you know that member B is three times as fast, on average, as member A at serving requests (for example).
When you make use of Priority Group Activation, and if you set 'Less than 2' (as per your above example) and all pool members are available member A won't get used. However, if and when one of the other servers fails, there are no less than 2 members available in the (priority 3) group, and so member A comes online. You can have as many priority groups as you wish and create a cascading effect. The idea is that if the pool members are unreliable or often taken offline for maintenence, there will be other servers that can take their place whilst they are absent from the pool.
Let us know if you need anything else!
