swapon(2)                                                         swapon(2)




 NAME    [Toc]    [Back]
      swapon - add swap space for interleaved paging/swapping

 SYNOPSIS    [Toc]    [Back]
      #include <unistd.h>

      int swapon(const char *path, ...
                 /* [int min,
                     int limit,
                     int reserve,]
                    int priority */ );

    Remarks    [Toc]    [Back]
      The ANSI C ", ..." construct denotes a variable length argument list
      whose optional and required members are given in the associated comment
      (/* */).

 DESCRIPTION    [Toc]    [Back]
      The swapon() 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.  Space is taken from the lower-priority
      systems first.

      swapon() can be used only by users who have appropriate privileges.

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

      In this form, swapon() 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
      previously 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
      swapon() makes the blocks on the file system rooted at path available



 Hewlett-Packard Company            - 1 -      HP-UX 11i Version 2: Sep 2004






 swapon(2)                                                         swapon(2)




      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 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.

 ERRORS    [Toc]    [Back]
      If swapon() fails, errno is set to one of the following values.

           [EACCES]       A component of the path prefix denies search
                          permission.

           [EALREADY]     The device associated with path already has swap
                          turned on.

           [EBUSY]        The device associated with path is already in use.

           [EEXIST]       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.

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

           [EIO]          Unable to read the device associated with path.

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

           [ENAMETOOLONG] The length of the specified path name exceeds
                          PATH_MAX bytes, or the length of a component of
                          the path name exceeds NAME_MAX bytes while
                          _POSIX_NO_TRUNC is in effect.

           [ENODEV]       The device associated with path does not exist.

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

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




 Hewlett-Packard Company            - 2 -      HP-UX 11i Version 2: Sep 2004






 swapon(2)                                                         swapon(2)




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

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

           [ENOTDIR]      A component of the path is not a directory.

           [ENXIO]        The device associated with path could not be
                          opened.

           [EPERM]        The effective user ID is not a user with
                          appropriate privileges.

           [EROFS]        The device associated with path is read-only.

 WARNINGS    [Toc]    [Back]
      On systems running VxVM 3.5, the swap volumes to be configured for
      system crash dumps should be created with the usage type as swap
      during the creation of the swap volume.  Not doing so will cause a
      dump corruption.  You could use the -U option of vxassist(1M) 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.

 AUTHOR    [Toc]    [Back]
      swapon() was developed by the University of California, Berkeley.

 SEE ALSO    [Toc]    [Back]
      swapon(1M), vxassist(1M).


 Hewlett-Packard Company            - 3 -      HP-UX 11i Version 2: Sep 2004