1 proxy, 1 mailstore, 1 proxy+mailstore. How many memcaches and where?
I started my latest setup with 1 server, that did everything (proxy, mailstore, mta, ldap master, …). (lets's call the server z1)
I recently added a new mailstore (+ ldap replica) (called z2) and a proxy-only server (called z3). The intention is that all new clients use the proxy-only server to talk to, and to push existing ones to use the proxy as well.
All runs well, but I have 2 memcache servers at the moment. One on z1 and one on z3. It seems that people with mailboxes on z2 can't login via z3 if z1. It seems z3 depends on the memcache on z1 (and maybe even on the routing engine on z1).
How to work around this? Remove the memcache on z1? What if next year I want to add a new proxy to provide redundant proxies? Will z3 stop working if any memcache is down?