Explanation: It is normal for Linux systems to use swap, even if physical memory (RAM) is always free. The kernel moves memory pages that are hardly used into swap memory. The use of swap becomes a problem only when the amount of available physical memory is insufficient, and the kernel is forced to constantly move memory pages to the swap space and back to physical memory, just to keep the applications running. In this case, the System Monitor Applications show a large amount of disk I/O activity.