When you install Linux, you’re asked to configure a swap, or virtual memory, partition. This special disk space is used to temporarily store portions of main memory containing programs or program data that are not needed constantly, allowing more processes to execute concurrently. An old rule of thumb for Linux is to set the size of the system’s swap space to be double the amount of physical RAM in the machine. For example, if your system has 512 MB of RAM, it would be reasonable to set your swap size to at least 1 GB. These are just guidelines, of course. A system’s utilization of virtual memory depends on what the system does and the number and size of processes it runs. As hard disk and memory gets cheaper and Linux application footprints grow, the guidelines for determining swap sizes become more and more about personal preference. However, when in doubt, using twice the amount of main memory is a good starting point.