I remember reading a post which said that the Swap needed to be about 2 x the size of RAM (or maybe a little more) to use suspend to disc.
The swap is 2 x ram rule is an old concept that harkens back to the time when ram was very expensive and the performance hit taken when using swap was considered an acceptable trade off for the cost of the hardware.
Questions, eh? Well, here's one: why Suspend to RAM, anyway? I thought the idea behind Suspend was to first freeze the system, and then suspend the current state to an imagefile, so that when you turned the machine back on again it could read said imagefile, restore the previous state, and resume system operation from the same point where it had previously been suspended. Suspend to RAM doesn't make sense to me, because as soon as the machine turns off that RAM is erased anyway - so what would be the point?
Suspend to ram (also known as sleep) has no need for swap; all open applications and active files are held in RAM and the machine then enters a very low power state (5 watts or so), the main purpose being to ensure the RAM is kept powered thus preserving the machine state (note the system is not powered off
). this allows the machine to be woken up and used very quickly without having to wait for the full boot process. It is only really used on desktop systems or for short periods on laptops, as you point out, if you lose power you lose anything unsaved and possibly cause file damage.
Suspend to disk (also known as hibernate), is a very similar process, the difference being that an image of the above state is is saved to swap and the machine is then powered off.
From this it can be seen that the swap needs to be at least as large as ram. If you find that you use the swap when performing memory intensive tasks on the machine (such as video or audio work), and you intend to use suspend to disk, then you should configure your swap file to at least equal the peak swap usage plus the installed RAM
As you're using an eeepc and not concerned about Hibernating the machine I would suggest you monitor your swap usage (use free -t
in a shell window), and if you don't use it remove it, or reduce it to a level you are happy with. If this is a new build you are contemplating, start with swap = RAM with a view to reducing it if it is not used.