System Administration Guide, Volume 1

How to Create a Swap File and Make It Available

  1. Become superuser.

    You can create a swap file without root permissions, but it is a good idea for root to be the owner of the swap file to avoid accidental overwriting.

  2. Create the swap file.

    # mkfile nnn[k|b|m] filename

    The swap file of the size nnn (in Kbytes, bytes, or Mbytes) and name you specify is created.

  3. Activate the swap file.

    # /usr/sbin/swap -a /path/filename

    You must use the absolute path name to specify the swap file. The swap file is added and available until the file system is unmounted, the system is rebooted, or the swap file is removed. Keep in mind that you can't unmount a file system while some process or program is swapping to the swap file.

  4. Add an entry for the swap file to the /etc/vfstab file that specifies the full path name of the file, and designates swap as the file system type, like this:

    /path/filename   -      -       swap     -     no     -
  5. Verify that the swap file is added.

    $ /usr/sbin/swap -l

Example--Creating a Swap File and Making It Available

The following examples shows how to create a 24 Mbyte swap file called /files/swapfiles.

# mkdir /files
# mkfile 24m /files/swapfile
# swap -a /files/swapfile
# vi /etc/vfstab
(An entry is added for the swap file):
/files/swapfile   -      -       swap     -     no     -
# swap -l
swapfile             dev  swaplo blocks   free
/dev/dsk/c0t2d0s1   32,17      8 205624 192704
/files/swapfile       -        8  40952  40952