How to Create a Swap File and Make It Available

Steps

1. Become superuser.

   You can create a swap file without root permissions. However, to avoid accidental overwriting, root should be the owner of the swap file.

2. Create a directory for the swap file, if needed.

3. Create the swap file.

   # mkfile nnn[k|b|m] filename

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

4. 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.

5. 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, as follows:

   /path/filename - - swap - no -

6. Verify that the swap file is added.

   $ /usr/sbin/swap -l

Example 19–1 Creating a Swap File and Making It Available

The following examples shows how to create a 100–Mbyte swap file called /files/swapfile.

# mkdir /files
# mkfile 100m /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/c0t0d0s1   136,1      16 1638608 1600528
/files/swapfile        -       16 204784  204784