NAME

swapon − enable additional device or file system for paging and swapping

SYNOPSIS

/etc/swapon −a
/etc/swapon name|directory min limit reserve priority

DESCRIPTION

Swapon is used to enable additional devices or file systems on which paging and swapping are to take place.  The system begins by swapping and paging on only a single device so that only one disk is required at bootstrap time.  Calls to swapon normally occur in the system multi-user initialization file /etc/rc making all swap space available so that the paging and swapping activity is interleaved across devices and file systems of the same priority. 

Normally, the −a argument is given, causing all devices marked as swap and all file systems marked as swapfs in /etc/checklist to be made available.  By using the first field (special file name) or (directory) the system determines which block device or file system to use. The special file name specified for each swap entry in /etc/checklist must specify a block special file.  The directory specified for each swapfs entry in /etc/checklist must specify a directory on the file system to be enabled. 

The second form of swapon announces individual block devices or file systems to be used for paging and swapping.  Block devices must have been setup at system configuration time.  File system swap is dynamic and can be added on a running system, but not removed. 

name must specify a block special file if a block device is to be enabled for swapping,

directory specifies which file system is to enabled for swapping. 

The min limit reserve and priority parameters default to zero and only have meaning if the first parameter passed to swapon is a directory. 

min indicates the number of file system blocks to take from the file system at the time that swapon() is called. 

limit indicates the maximum number of file system blocks the swap system is allowed to take from the file system. 

reserve indicates the number of file system blocks that are saved for file system use only. 

priority indicates the order in which space is taken from the file systems used for swap.  Space is taken from the lower priority systems first. 

WARNINGS

There is no way to stop paging and swapping on a device or file system. 

Exercise due caution when enabling swap space on a device or file system that may be unmounted during system operation or removed from the system. 

The system will allocate no less than the amount specified in "min", however, to make the most efficient use of space, more than the amount requested might be taken from the file system.  The actual amount taken will not exceed the number of file system blocks indicated in "reserve". 

If more swap blocks are needed for one particular file system than those already added, additional calls can be made to swapon(). 

EXAMPLES

swapon /swap 10 3000 20 0

swapon /mnt 0 0 0 1

swapon /extra 0 2580 1000 2

FILES

/dev/dsk/c#d#s#Normal paging devices. 

AUTHOR

Swapon was developed by the University of California, Berkeley. 

SEE ALSO

swapon(2), checklist(4). 

Hewlett-Packard Company  —  HP-UX Release 7.0: Sept 1989