Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Administering a System: Managing Disks and Files
Managing Swap and Dump
Chapter 6662
Managing Swap and Dump
This section explains how to manage your system’s swap space, including
determining how much and what type of swap space the system needs,
and how to add or remove swap space as the system’s needs change.
It also explains how to configure your dump area.
For additional information, see also:
• “Setting Disk-Management Strategy” on page 76
• “Implementing Disk-Management Strategy” on page 393
• The book Disk and File Management Tasks on HP-UX.
Types of Swap Space
There are three types of swap space: device swap, file system swap, and
pseudo-swap space. Each is used differently by the system and has its
own advantages and disadvantages.
Device Swap
Swap space is initially allocated when you configure your disks. Device
swap space occupies a logical volume or partition, which is typically
reserved expressly for swapping purposes. This space may also be
configured as a dump area; see “Configuring Dump” on page 671.
Device swap can only be used locally; device swap cannot be accessed
remotely by clients using NFS.
Device swap space is quickly accessed because the operating system can
get to the logical volume or partition directly to perform large I/Os.
File System Swap
You can additionally use available space in a file system for swap space.
Setting up such file system swap space allows for extra swap if there is
occasional need for more than the allocated device swap space. It is used
only when device swap space is insufficient.
When your system needs extra swap space, file system swap allows you
to use existing file system space rather than reserving an entire
dedicated logical volume or partition. However, because file system swap