Hi, Li Ma schrieb: > 1. I was told Tomcat can only run max 3 nodes in cluster smoothly. What's > your milage?
Cluster in the sense of horizontal scaling (load-balancing): no limitations. Cluster with state replication of sessions (assuming TC 5.5): you break down your cluster into groups of 2 to 4 nodes, and replucation is any-to-any inside a group and no replication between groups. Technically spoken a group is a cluster of nodes and your whole farm consists if many small clusters. mod_jk load-balancing can be configured to respect those clusters during fail-over by defining "domains" in mod_jk. Be careful: state replication is complicated and expensive. If your session doesn't have a lot of value and it's cheap for your costumers to relogin after node failure, you don't want to use state replication. Horizontal scaling and a good load-balancing suffices in this case. Only if sessions are valuable, you might want to protect them against failure by real clustering. > 2. This is not related to Tomcat, but if a site has N registered users, > what > is the average percentage of concurrent user should I expect? I ask this > because my client wants 1million registered users. But he wants me to > support 20% concurrent users, which I believe is way impossible! But I need > to have some number to give him the right sense. This is also important for > me to setup the target. This really depends mostly on the business. Concurrent Users = Number of sessions ~ Memory constraints Concurrent Requests = Concurrent Users * Click Rate of User * Response duration of request ~ CPU and Thread constraints Concurrent Users and Click rates very much depend on the business the app provides. Some Aps are used as "Login in the morning, keep session open all day and expire during night", others are "Login, do something and log out/expire". Click rates can be very high (Ajax, static requests, fine grained user interfaces" or low "transaction type system, long prepartion times locally in browser for complex forms". Regards, Rainer --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
