On 11/23/05, Dave Watts <[EMAIL PROTECTED]> wrote: > > > > How do you span sessions across ColdFusion servers if you > > > > aren't using Enterprise? > > > > > > You don't. > > > > Isn't it all a matter of how you cluster the machines though? > > I mean, if you want to use sessions in a clustered environment, > > you just need to make sure that your load balancer uses sticky > > sessions. Basically, the goal is not to ever toss users between > > servers, but just assign users to a server based on the load > > balancing parameters when they first land on your site. > > If you do that, you aren't spanning sessions across CF servers. This > approach is often referred to as "sticky sessions". If you use sticky > sessions, you don't get failover, only load-balancing. This may or may not > be acceptable, depending on your business needs and general server > stability.
Furthermore, you get a less powerful version of load-balancing -- incoming initial user sessions are balanced according to load (or whatever balancing scheme is being used) but once the user is *on* a server, they're on it for the sessions (thus the "sticky"). So if a server slows down b/c of a runaway process for example, *new* users get balanced to the less loaded servers, but the folks on the server with the slowdown are stuck. This is in contrast to active loadbalancing without sticky sessions where the user gets the least loaded server (or whatever is set in the balancing rubric) on *every* request. As an aside, implementing session-aware clustering can actually degrade performance, even when done "right". Using files to store session for example, is a common approach in both the LAMP stack and RubyOnRails for scaling horizontally across N servers -- but your chokepoint becomes the SAN or whatever storing the data. Even more advanced solutions like memcached (eg LiveJournal and Slashdot) or J2EE session clustering (eg CFMX) have problems b/c replicating data between multiple nodes takes time when the data is very active. It's always a balance of reliability vs performance. -- John Paul Ashenfelter CTO/Transitionpoint (blog) http://www.ashenfelter.com (email) [EMAIL PROTECTED] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Find out how CFTicket can increase your company's customer support efficiency by 100% http://www.houseoffusion.com/banners/view.cfm?bannerid=49 Message: http://www.houseoffusion.com/lists.cfm/link=i:4:225247 Archives: http://www.houseoffusion.com/cf_lists/threads.cfm/4 Subscription: http://www.houseoffusion.com/lists.cfm/link=s:4 Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4 Donations & Support: http://www.houseoffusion.com/tiny.cfm/54
