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I have been advised by my friend that when running Java on virtual environment, it can suck RAM quite drastically over time and adding more RAM won't make any difference. Is this true? Why is this true for Java but not for other platform like PHP or Ruby on Rails?

I also saw another thread on ServerFault that running Cassandra on Linode is less advisable than running it on Rackspace or EC2? Why would it be any different?

Thanks heaps for the explanation.

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up vote 2 down vote accepted

To answer your first set of questions, I would say that your friend's statement is inaccurate at best. You can have an equally poorly running application on straight up hardware; I unfortunately know this as a fact (Badly developed vendor app on large hardware -- still performs poorly). It really boils down to two major items:

  1. How well the application was written
  2. How well the JVM is tuned to run said application

I have run both well behaved applications and poorly written Java applications. Conversely, I have also come across the same with other frameworks like PHP and Perl.

This isn't to say a virtualized environment is completely blameless here. You have to understand the requirements of your application and size your virtual machine(s) accordingly. Many people want to "cheap it out" and get the smallest VM configuration and then wonder why their application is either swapping like mad or throwing OutOfMemory exceptions.

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Make sure that you refer to this documentation ( before you decide to ask your Sysadmin for the memory size.


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