Thanks for the replies Chuck as always; I meant to say that sooner. =P I am also sorry this reply is a week overdue, however I have been tied up for a week. Let me explain the situation a little more thoroughly and see what your thoughts are then:
For several critical applications such as SSO and student registration, we want them clustered over multiple servers behind a load balancer. The SSO application's load consists of users logging in and ticket processing. The student registration application's load consists of thousands of students pounding at a handful of servers constantly in hopes they can schedule their classes before they fill up. It is like people watching an eBay auction and constantly refreshing the page to see if they have the winning bid and upping it whenever they aren't. If a server goes down, the load balancer will forward traffic to the others such that no one will experience interruption of service. Obviously, this requires the application servers to be clustered such that their sessions are replicated with one another. Given that our SSO solution is currently clustered among three machines: 1. Does Tomcat keep all session information strictly in RAM or does it swap out to disk? If it swaps out to disk, is there any way to configure how much session information can be kept in RAM? 2. What commonly used formulas are there to determine sufficient RAM based on load size? I am currently reviewing logs from our peak application usage as well as an average day to determine the number of logins / second. 3. Is it better to split large clusters into smaller ones with a few nodes replicating to the other clusters? (Example below with nodes denoted by "O") SSO CLUSTER -------------- | CLUSTER A | | | | O------O | | \ / | | O--O | | | | | |----|--|----| | | | | | O--O | | / \ | | O------O | | | | CLUSTER B | -------------- I posed my original question (Can Tomcat write session information to disk or database like the Apache HTTP) because it seemed more scalable as: 1. Our SAN has several terabytes worth of space so session information can grow easily. 2. Reduces RAM bottleneck 3. Reduces network traffic to replicate session information I would appreciate any thoughts and alternatives you have to offer! Thanks, Andrew R Feller, Analyst University Information Systems 200 Fred Frey Building Louisiana State University Baton Rouge, LA, 70803 (225) 578-3737 (Office) (225) 578-6400 (Fax) -----Original Message----- From: Caldarale, Charles R [mailto:[EMAIL PROTECTED] Sent: Wednesday, February 27, 2008 2:17 PM To: Tomcat Users List Subject: RE: Storing sessions to disk like Apache HTTP server > From: Andrew R Feller [mailto:[EMAIL PROTECTED] > Subject: RE: Storing sessions to disk like Apache HTTP server > > Actually, the system we are concerned about will have tens of > thousands of concurrent users. Number of users != number of sessions, unless they all log in and stay logged in concurrently (or you have a very high session timeout setting). Regardless, given the price of memory and the ready availability of 64-bit platforms, there's no sense in over-engineering this. - Chuck THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers. --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
