Hi all,

I'm investigating power saving options for my laptop. I don't need help with the implementation, just a bit of guidance beforehand.

Can someone tell me the difference between:

suspend to RAM
suspend to disk
hibernation

The first two I guess are pretty obvious. It's the latter I'm not sure about.

Please advise.


Mark.

Okay, after a more thorough STFW I have ascertained that:

• Suspend to disk - hibernate
• Suspend to RAM - standby

Someone correct me if I'm wrong...


M.

Suspend to disk is indeed hibernate. It uses your swap partition (or a swap file, but I don't quite know how to set that up) to write the contents of the RAM and turns off your PC. When you start it up, as long as you have a line like append="resume=/dev/hda1" in your /etc/lilo.conf (assuming that your swap partition is /dev/hda1), your system will boot into the same state it was in when you hibernated. It should be noted that the default Slackware kernels do not have suspend to disk enabled by default, and also that these ACPI functions have greatly improved since the 2.6.21.5 kernel, so it would be best to use a recent kernel.

Suspend to RAM means that everything in your PC powers down except for your RAM (or something like this -- I am sure *some* other stuff gets powered as well, but it's very little). Suspending to RAM leaves my PC completely silent, and I've left it suspended for several hours with no ill effects. This functionality has also improved immensely since the 2.6.21.5 kernel (my PC crashed once or twice during suspend to RAM using that kernel but has never crashed using a 2.6.24.x kernel).

Standby basically means only a few things power down -- it's like "standby" in Windows. It's not really very useful considering how much better suspend to RAM is, in my opinion, but it's still an option.

You don't need anything in lilo.conf, at least i never had an s2disk is still fine.

Hmm I could only get hibernation to work with the 'resume=..' in lilo.conf.

Hi,

Thanks for your replies.

I'm gonna go with suspend to RAM, although I can't at the moment as X crashes 9 times out of 10 when I shutdown / restart. This is a problem with X and the intel driver (Dell D430), which I hope will be fixed in 12.1.


M.

You can define a default resume partition in the kernel, in which case you don't need it in lilo.conf.

Brian

Yes, I just presumed others did too.

I just couldn't get the hardware in my laptop to work with the standby or hibernate in slackware 11 with a 2.6.17.13 kernel.

Instead, I optimised the boot-up so that from completely off to command prompt it was about as fast as win xp coming out of standby on that laptop (and much faster than hibernate). Getting to the KDE desktop took longer, but battering away at keys and using pico is perfect for my daily commute on the train (emails, drafts to be tarted up later in OOo). Another advantage of this is that there is no steady drain on the battery.

I'll give hibernate/standby another go when 12.1 is ready.

I had to use tuxonice (formerly suspend2) to get it to work under 2.6.17.

Brian