A common issue is that a user’s login state is stored locally by a web server but not communicated to replicas. When the load balancer receives future requests from the same user, if they are sent to a different replica the user will be asked to log in again. This will repeat until the user has logged into every replica. Solutions to this problem are discussed in Section 4.2.3.
Worked with a customer many years ago whose app servers worked this way. On first request to www, customer redirected to another host and remained sticky there for remainder of session. I think the only way to maintain state outside of the app server was in the db, but the app server may have provided some in-memory cache that forced additional session stickiness at the next layer of stack as well?...Netscape application server, anyone?
This is years before the advent of memcached (2003). What cache server approach did people use before that? Or in dial-up days it didn't matter and it didn't exist?
