Question regarding load balance method

You really have two options here depending on how precise you need to be:

1. Ratio-based load balancing - setting ratios on pool members sounds exactly like what it is. You define a set of ratio values to each pool member (ex. 2:1, 10:2, etc.) and the pool members are load balanced according to these ratios (ex. 10 connections to member1 for every 2 connection to member2).

    

   https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-concepts-11-5-1/5.htmlunique_452626201

    

2. Connection limits - if you need more control than that, you can simply specify a connection limit for each pool member. Once that limit is reached the system does not send any new connections to that member.

    

So to answer your second question, if you cap server A at 10 connections, and server B goes down, server A will still only be able to serve 10 connections. This is usually a really good reason to use ratio balancing first and then apply a reasonable connection limit only if needed.