To my knowledge, a vanilla install of RHEL 5.x has no configuration to automate the release of the accumulated memory within the cache. This can become an issue when there's no more free memory for other applications.
I constructed a Ubuntu image with the intention on building a fresh Oracle middleware suite within it. I was receiving the error response, 'su: Authentication failure'. Turns out the the user root is disabled by default.
Here are the simple steps on how to check if you can execute the shell scripts on a unix server by using the
crontab functionality. Crontab is disabled by default, so this would need to be activated, this post assumes that you
already have the crontab functionality enabled
If you've ran out of memory on your VM, here's an older blog that outlines,
HOW TO: Expand existing hard drive space on a VM Oracle Linux.
Below elaborates the older post further. Below is the story on how to expand from 2GB to 6GB of space with a few Linux commands.