I have 16 Gigs of physical RAM. Not sure I understand hibernation, but I set my computer to go blank screen (sleep? or hibernate?) after 15 minutes. To activate the PC from this state, I either wiggle the mouse or I hit space bar or the Return key several times. It is functioning properly even when I do not have swap. I will study the manual to see if it shows how to add swap post install. It cannot hurt. Thanks.
Well, sleeping often just means to blank the screen and put the CPU in a power-saving state. It stops and the system continues to run, when any external activity is detected (keyboard, mouse, and so on). That has nothing to do with disk-space, which is also true for suspend, which (mostly) means "suspend to ram". Here all activity is ceased, processes put on hold until wake-up, which often is more restricted than a simple mouse movement ((special) keys or (notebook-)lid). For both events, running out of power means the total loss of processes and results, and in the worst case filesystem corruption.
"Hibernation" (to disk, this is why you need the swap-space) is somewhat similar to suspend, but here, all data, RAM-content, and states are written out to the disk. Once done, you can (but do not have to
) remove all power from the system. Once restored, special actions like opening the lid, pressing a reserved key or the power (soft!) switch will wake up the system. When this is done, it will be in the same state that you left it in before hibernation.
Roughly speaking, you can suspend a system for hours, may be days until the battery is depleted, while a hibernated system can pause "indefinitely" without taking damage.
