swapon(2)							System Calls Manual							 swapon(2)

NAME

       swapon() - add swap space for interleaved paging and swapping

SYNOPSIS

   Remarks
       The ANSI C "" construct denotes a variable length argument list whose optional and required members are given in the associated comment

DESCRIPTION

       The system call makes a block device or a directory named path available to the system for paging and swapping.

       priority indicates the order in which the swap space from the device or file system is used.  It has a range of 0 (highest) to 10 (lowest).
       Space is taken from the lower-numbered systems first.

       can be used only by users who have appropriate privileges.

   If path names a block device file
       makes it available to the system at the specified priority for allocation for paging and swapping.

       In this form, takes only two arguments: the path to the block device file, and the priority.

       The device associated with path can be a device already known to the system, defined at system configuration time, or it can  be  a  previ-
       ously unspecified device.

       If  the device was already defined at system configuration time and also has a start and/or size defined for that swap device, these values
       are used.

       Otherwise, if a filesystem exists on the device, swap is added following the filesystem, or if no filesystem exists, the complete device is
       used for swap.

       See the appropriate system administrator's manual for information on how the size of the swap area is calculated.

   If path names a directory
       makes the blocks on the file system rooted at path available for paging and swapping.

       The min, limit, and reserve arguments are passed and used only if the path argument names a directory.

       min indicates the number of file system blocks to take from the file system when 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.

       For  a  pre-existing directory swap, a value of -1 for min, limit, reserve, or priority will keep the value unchanged.  This can be used to
       change selective values without affecting others.  For example, if priority of a pre-existing directory swap needs to  be  changed  without
       affecting the values of min, limit, or reserve, one can specify the new priority value and pass -1 for other arguments.

       The  size  for the file system blocks mentioned above is the preferred file system block size.  The preferred file system block size can be
       obtained by the call.  The value of min, limit, or reserve is rounded up to the tunable size.

ERRORS

       If fails, is set to one of the following values.

	      A component of the path prefix denies search permission.

	      One of	     priority, min, limit, or reserve arguments is invalid.

	      The device associated with
			     path already has swap turned on.

	      The device associated with
			     path is already in use.

	      The device associated with
			     path was specified at system configuration time to add swap at a specified location, but that location is	within	an
			     existing file system on the device.

	      The LIF header on the device associated with
			     path contains inconsistent directory data.

	      Unable to read the device associated with
			     path.

	      Too many symbolic links were encountered in translating the path name.

	      The length of the specified path name exceeds
			     bytes, or the length of a component of the path name exceeds bytes while is in effect.

	      The device associated with
			     path does not exist.

	      The system-imposed limit on the number of swap file entries has been reached.

	      There is is not enough available space
			     on the specified file system or device.

	      The device associated with
			     path was specified at system configuration time to add swap following the file system, but no file system was found.

	      The	     path argument is not a block special file or the root directory of a file system.

	      A component of the path is not a directory.

	      The device associated with
			     path could not be opened.

	      The effective user ID is not a user with appropriate privileges.

	      The device associated with
			     path is read-only.

WARNINGS

       On  systems  running VxVM 3.5, the swap volumes to be configured for system crash dumps should be created with the usage type as during the
       creation of the swap volume.  Not doing so will cause a dump corruption.  You could use the option of to do the same.

       No means is available to stop swapping to a device.

       The system allocates 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.

       Swapping to a file system is usually slower than swapping to a device.

       Once file system blocks have been allocated for swap space, the file system can not be unmounted unless the system is rebooted.

       is the replacement for is to be obsoleted at a future date.

AUTHOR

       was developed by the University of California, Berkeley.

SEE ALSO

       swapon(1M), vxassist(1M), swapctl(2), privileges(5).

								  TO BE OBSOLETED							 swapon(2)