[ale] Linux swap space vs hibernate, power shutdown settings

[Ron Frazier]

Hi all,

I've verified experimentally that Ubuntu 10.04 will not let the machine 
hibernate if there is no swap space.  This seems to confirm what I read 
elsewhere that the swap space is used for the hibernation data.  
(Windows uses a separate file.)  I believe that you must have a swap 
space equal to and perhaps a bit larger than RAM in order to hibernate.  
I prefer not to use standby or suspend since, at least in terms of 
Windows in the past, that has been known to cause data corruption since 
the standby data is in RAM and could be lost if the battery is weak, 
etc.  As I write this, I'm noticing that my laptop offers a suspend 
option in Linux and the desktop does not.  In any case, if I don't want 
to do a full shutdown, I prefer to have all the system state data saved 
to the disk and all the power shut down.

I'd be interested to know whether setting the power settings to shutdown 
or hibernate is better in case the UPS battery gets critically low after 
a power failure.  In my case, the UPS only runs 3-4 minutes on the 
desktop, so I currently have that setting on shutdown.  I figured the 
system can shut down faster than it can hibernate.  If anyone knows, I'd 
also like to know how to set the shutdown time on the Gnome power 
manager.  If, for example, the system shuts down when the UPS is at 10% 
after a power failure, this is bad for me since that amounts to about 18 
seconds of warning before the battery dies.  I don't think even Linux 
can shut down that fast.

Sincerely,

Ron

-- 

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Ron Frazier

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linuxdude AT c3energy.com