When you boot (or enable swapping manually) you should see

   Adding Swap: NNNNk swap-space

If you don't see any messages at all you are probably missing

   swapon -av

(the command to enable swapping) in your /etc/rc.local or /etc/rc.d/* (the system startup scripts), or have forgotten to make the right entry in /etc/fstab:

   /dev/hda2       none       swap       sw

for example.

If you see:

   Unable to find swap-space signature

you have forgotten to run mkswap. See the manual page for details; it works much like mkfs.

Running, free in addition to showing free memory, should display:

             total       used       free
   Swap:        10188       2960       7228

If typing "cat /proc/swaps" reveals only file or partition names, but no swap space information, then the swap file or partition needs re-initialization.

Use fdisk (as root) to determine which partition on a hard drive has been designated as the swap partition. The partition still needs to be initialized with mkswap before enabling it with swapon.

[Andy Jefferson, Steve Withers]