13장. Getting started with swap

Swap space in Linux is used when physical memory (RAM) is exhausted. When more memory is required and RAM is full, inactive memory pages are moved to swap. Swap helps systems with limited RAM but is no substitute for adding more actual memory.

Swap space is located on hard drives, which have a slower access time than physical memory. Swap space can be a dedicated swap partition (recommended), a swap file, or a combination of swap partitions and swap files.

In years past, the recommended amount of swap space increased linearly with the amount of RAM in the system. However, modern systems often include hundreds of gigabytes of RAM. As a consequence, recommended swap space is considered a function of system memory workload, not system memory.