Don't forget to leave some space for the OS' buffer cache. If your app.s do a lot of I/O then they can benefit a great deal from having the most commonly accessed storage blocks cached all the time.
W.r.t. Tomcat tuning this means you don't try to use up all of physical memory with Tomcat instances. Set the heap maxima so that the total, plus fixed overhead for Tomcat itself and the JVM, leave enough room for the OS and generous caches. You'll have to monitor and retune iteratively to find out how much "generous" should be. If you see *any* swapping then you probably ought to reduce the maxima until it goes away. Also monitor how much of your heap space is actually used during peak usage periods. Giving your app.s a huge slab of memory is a reasonable first step in exploring performance issues, but you may be unable to make use of all that memory in your app.s. In that case you may want to see if giving some of it back to the OS (see caching above) would give better overall performance. -- Mark H. Wood, Lead System Programmer [EMAIL PROTECTED] Typically when a software vendor says that a product is "intuitive" he means the exact opposite.
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