Question on Ratio Load Balancing Method

Hi Humam, 

Initially I was just as PSFletchTheTek a bit sceptic as the reason for it, but that makes sense now, thanks for the additional explanation (though I'll give you another way to achieve the same below)

When you configure the ratios as 100/0/0, it will indeed go all to the first pool member and the other two pool members don't get any traffic. If the first pool member were to go down, it then indeed uses the alternate load balancing method to figure out where to send the traffic. If that is configured as Round Robin, it will be split 50/50 between the two remaining pool members. If the alternate load balancing method is set to Global Availability, it will all go to whichever is the next virtual server in the list. 

I've just tested this in my lab (as I wasn't 100% sure how the Ratio 0 would work out in practise), and your assessment seems correct indeed. When I disable my first pool member (the one with ratio 100), the alternate load balancing method kicks in. 

Saying that, would it be an option to switch to Global Availability load balancing altogether? This will always make it follow the order in which the pool members are in the pool. Initially, all traffic goes to pool member 1, if that one goes down, everything goes to pool member 2 and so on. This is a load balancing method that is often used between Active and Standby systems, and I think your database system may also benefit from it. 

More info: https://techdocs.f5.com/en-us/bigip-14-1-0/big-ip-dns-load-balancing-14-1-0/global-server-load-balancing.html

Hope this helps.