Sticky sessions are where a load balancer is smart enough to send all requests from a given user session to a single server in the cluster. I.e. instead of delegating each individual request to one of the servers, it keeps track of which requests belong to each session, and ensure that a single session always goes to the same server.
You don't have to risk losing sessions when you fail over; there are two ways to avoid it. 1) Use CF Enterprise, which includes session replication so all servers can process requests from any session. Still a good idea to use sticky session, because replication isn't instantaneous. 2) don't use session storage, instead use client variables (or something like it), where the data is stored in a shared location (the DB), instead of in memory. That gives you the ability to have any request go to any server and that server will be able to get the needed data from the DB. This obviates the need for sticky sessions, though you can have a lot of weird concurrency issues, because of non-atomic operations on the client variables. If you're considering this mechanism, I'd highly recommend NOT using client variables, and instead using something home grown that addresses the concurrency issues. We use the latter approach, because we need to have perfect uptime (aside from occasional scheduled maintenance), with no session loss if something breaks. The former option is far more performant, but it's still possible to have session-related issues on a failover. The latter also doesn't require CF Enterprise, which saved us almost $20,000 in CF licensing (though we poured most of that back into developing a custom client variables implementation). cheers, barneyb On 8/30/05, Dustin M Snell [Network Automation] <[EMAIL PROTECTED]> wrote: > Thanks for all the answers so far, > > Hmm - so it may be possible after all if I am willing to loose the sessions? > What are sticky sessions? > > -Dustin Snell > Network Automation, Inc > > -- Barney Boisvert [EMAIL PROTECTED] 360.319.6145 http://www.barneyb.com/ Got Gmail? I have 100 invites. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| 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:4:216879 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
