AIX uses virtual memory to address more memory than is physically available in the system. The management of memory pages in RAM or on disk is handled by the Virtual Memory Manager (VMM). Virtual-memory segments are partitioned in units called pages. A paging space is a type of logical volume with allocated disk space that stores information which is resident in virtual memory but is not currently being accessed. This logical volume has an attribute type equal to paging, and is usually simply referred to as paging space or swap space. When the amount of free RAM in the system is low, programs or data that have not been used recently are moved from memory to paging space to release memory for other activities.
The following sections provide more information about the VMM and paging space. For performance implications related to paging spaces, see the section on performance considerations of paging spaces in AIX 5L Version 5.2 Performance Management Guide. For information about managing paging spaces or virtual memory, see Paging Space and Virtual Memory in AIX 5L Version 5.2 System Management Guide: Operating System and Devices.