Cirrostratus
CumulonimbusFor all cache servers best option is destination persistence (Sticky perssitence).
Please test in your environment and let us know the status.
Destination address affinity persistence You can optimize your server array with destination address affinity persistence. Destination address affinity persistence, also known as sticky persistence, directs requests for a certain destination IP address to the same server, regardless of which client made the request. This type of persistence provides the most benefits when load balancing caching servers. A caching server intercepts web requests and returns a cached web page if it is available. In order to improve the efficiency of the cache on these servers, it is necessary to send similar requests to the same server repeatedly. You can use the destination address affinity persistence type to cache a given web page on one server instead of on every server in an array. This saves the other servers from having to duplicate the web page in their cache, wasting memory.
CirrostratusVS-A has source_addr persistence, because here VS-A sees the real client IPs and can persist based on that info.
VS-B has none (only a hard wired via iRule for a certain website). Source_addr would is useless, because the VS-B only sees the two IPs of our proxies. If I choose source_addr, the traffic would only use 2 of the nodes in pool B. I want to use as many nodes in pool B as possible and persist on those connections based upon the real client IP. I thought of inserting a X-Forwared-For header in VS-A, so VS-B has something to base persistense on, but I really don't know how.
Btw. the proxies in Pool B seem to strip headers like "X-Forwared-For". So the header is not available in the HTTP_RESPONSE.