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10.4: Enable safe sleep on some older Macs
Authored by: theocrates on Nov 18, '05 01:17:52PM
I posted a couple of comments at Andrew's web site (see them under my other alias, "Shocktrooper") regarding Safe Sleep and third-party batteries that I thought might be useful mentioned here, too.

In a nutshell, third-party batteries do not support Sleep mode, so they do not auto-sleep like Apple batteries when they run low; instead, they simply run down and cut out the computer, which means you lose all unsaved data and need to reboot to get up and running again. After activating the Safe Sleep hack, however, I discovered that when my battery ran down and cut out my computer, pressing the power button did not reboot but restored the Safe Sleep image instead. Huh?! I thought Safe Sleep only worked when your computer lost power while it was sleeping?

I have now replicted this result four times with no problems. Still, I can't quite explain this behavior, and the only thing Andrew says is that
[w]hen your Mac is set to sleep, it will now enter regular Sleep mode first (consuming minimal power). It will only enter Safe-Sleep if the battery is very low on power, or is unpluged [sic].
which seems to leave open the possibility that the computer only need be low on power, but not actually sleeping, to go into Safe Sleep mode. But this is not clear here and I have not seen any posts that specifically do talk about this issue.

In any event, I'm still happy that I can run down my battery without losing any unsaved data. But it would be cool if someone could clear up the issue for me. Anyone else out there with third-party batteries that can confirm my results or give a clearer explanation of what's happening here?

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10.4: Enable safe sleep on some older Macs
Authored by: saint.duo on Nov 18, '05 02:36:43PM

Sleep - in and of itself, is just closing the lid or selecting sleep, and being able to wake the computer by opening the lid or pressing a key, and coming back to where you were. This is supported by all batteries, as the computer is just going into a low power mode.

Sleep Swap is where you can remove a battery, and put in a fresh one and then be able to actually wake the computer back up, not having to boot it. This only works on PowerBooks (not the 12"), due to a backup battery or capacitor in the computer (depending on the model)

Safe Sleep monitors the charge level of the battery, and if during sleep, it gets to a certain point, saves the contents of RAM to the hard drive and safely shuts the machine down. The difference here is that before safe sleep, the computer would just turn off, possibly corrupting data.

I can only imagine that some 3rd party batteries may cause sleep swapping not to work, but I wouldn't know how.

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duo



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forgot deep sleep...
Authored by: saint.duo on Nov 18, '05 02:39:05PM

Deep sleep is probably what some 3rd party batteries do not support. Before safe sleep, when the battery reaches a certain point, the computer enters a sleep mode that cannot be woken from without the power adapter, but is using a very minute amount of battery power to preserve the contents of RAM. If you leave it long enough like this, then the computer will just shut off from complete lack of power.

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duo



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Works on iBook G4 1.33MHz
Authored by: emendelson on Nov 18, '05 05:00:22PM

As the heading says. With a current-model iBook G4, I can close the lid, wait for the pulsing sleep light to come on, remove the battery (and AC adapter if connected) - and then put back the battery, press the power button, and watch the machine re-emerge from sleep. Very nice - and something that every x86 laptop has had for years.



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Works on iBook G4 1.33MHz
Authored by: rawhead on Nov 18, '05 05:54:10PM

Uhh, you're talking about "Hibernate" right?

But has every Wintel laptop had the ability to be in regular "sleep" mode from which you can wake up in less than a second (actually, Wintel "sleep" is never that quick to wake up), then go into "hibernate" when the battery is running low or is suddenly removed?

I didn't think so.

I agree that not being able to selectively "force" a hybernate-like mode barring removing the battery after sleep is kinda sucky, but in terms of implementation, I love SafeSleep much better than what I can get on my Wintel machines right now (that is, each time I have to choose between sleep and hibernate)


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All these moments will be lost in time
Like tears in rain.
Time to die.



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10.4: Enable safe sleep on some older Macs
Authored by: xavierbdm on Nov 19, '05 07:36:26AM

Safe sleep does not what you say it does.
Setting up safe sleep on a machine, means that EACH time your laptop goes to sleep it will save the RAM to disk, EVERY time.
It is meant as a safeguard.
That is why you can pull out the battery and the power cord of a laptop that has the feature activated (but was put in sleep the "normal" way), and get it to wake up afterwards.
The laptop never wakes up to save RAM to disk when battery is low.
(that would be relying on battery having enough back-up juice left to actually do that. It is the Windows implementation. Clumsy, unefficient and dangerous too -imagine if the laptop is being bounced in a bag while waking up to enter hibernation-)

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iMac G4 17 800/512/80 + powerbook firewire G3 500/512/30



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