I intend to have a two tiered LB architecture: frontend LBs and "guard" backend LBs.
The "guard" backend LBs serve to guarantee that the backend server never has more than MAXCONN concurrent requests. Excess request are forwarded to some other backend using "first" load balancing. Since I now plan to use "cookie persistence" in the frontend LBs, I'm wondering if I can use the same cookie in the backend "guard" LBs to change the cookie to the new backend if the request is forwarded? That is, should all LBs, whether frontend or guard use the same cookie and the same pool of backends (only the "guard" backends would proxy to nginx/varnish while the "frontends" would proxy to the "guard" HAProxys)? Now that I can handle backend server changes occasionally, I want the change to stick for all subsequent requests by the user. Even if the server change was made by a second level guard HAProxy...
