We are thinking of the following LB algorithm but we are not sure if current HAProxy supports it: given a http request, LB should always forward it to a certain backend server (say Server A) based on its http parameter (e.g. request with parameter "Id=100" always go to server A). The only exception is: when the designated server (e.g. Server A) is down, then the request should be forwarded to another (fixed) server (e.g. Server B).
Thanks
