Tricky question on safe sleep when hibernatemode is 0 for charger and 3 for battery

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Tricky question on safe sleep when hibernatemode is 0 for charger and 3 for battery

Hi folks,

I've just replaced the HDD with a Samsung 830 series 512GB SSD in my 2010 Macbook Pro and done some pretty routine optimizations (e.g., trim on, localbackup off, sms off, etc.).

However when it comes to energy saver settings, it starts to look a bit hard to fit my needs:

1) I DO want it to sleep whenever possible regardless of the power source type (charger or battery).

2) In charger mode, I DON'T want it to dump the ram image to disk before sleeping.

3) In battery mode, I PREFER not dumping (but OKAY with it) before sleeping.

4) In battery mode, I DO want it to dump the ram image when the battery runs low.

Please note that this is a 2010 MBP, no support for the "standby"/"standbydelay" feature which can be found in later models. So if you set hibernatemode to 3, it will dump the whole 8GB ram image to disk every time RIGHT BEFORE it enters sleep mode. Every time, literally, even if you just let it sleep for only 20 seconds. This could be a nightmare for a SSD, so I definately don't want it unless I'm on battery (5% of my time).

So my choice is to set (via pmset) hibernatemode to 0 for charger mode, and 3 for battery mode and enable sleep in both modes. And that seems to satisfy the above 1), 2), and 3). But I'm not so sure if 4) is 100% supported, consider the below scenario:

a) The MBP is connected to a charger, now let it enter sleep mode. No ram image is written to disk because hibernatemode = 0.

b) Now you unplug the charger, it will continue sleeping, but on battery power. From now on, hibernatemode = 3.

c) Eventually the battery power will run low... What will it do? I doubt it will get a chance to dump the ram image although hibernatemode = 3, because it is still sleeping, right?

Unfortunately, it would take maybe 4 or 5 days to experiment with the above scenario (depending on how long it can sleep on battery power ) so I don't think I am allowed to do that myself.

Does anyone has any knowledge regarding MBP's behavior in this specific case? Thank you.

MacBook Pro, OS X Mountain Lion (10.8.4)

Posted on Jul 15, 2013 7:16 PM

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kmarasco

Level 1

5 points

Jul 26, 2013 7:38 PM in response to zuoy

I was playing around with this on my non-retina mid 2012 MBP tonight because I get terrible battery life when unplugged and sleeping. I'm running on an SSD and I'm running 10.8.4. From what I can tell my model doesn't support standby mode although it seems to work now (after some fiddling.) When I started looking into this issue I had no idea what exactly standby or autopoweroff did. They both seemed like they'd do the same thing. After a little reading it seemed what I was hearing was that standby applies to when the MBP is running on battery and autopoweroff applies when running on AC. The first thing I did was a "pmset -g" to see what my settings were. What I noticed was that my standby was set to 0 in battery mode by default. I don't think my MBP was ever going into hibernation mode. I would have thought I would have gotten better battery life when sleeping even without hibernation but who knows. I would put my MBP to sleep (close the lid) with 80-100% battery and then a day or two later the battery would be dead. I have friends who run Snow Leopard that would say they could go a long time in sleep mode.

Zuoy, I haven't tried what you are talking about specifically but I've got mine set to these settings:

Battery Mode:

hibernatemode 3

standby 1

standbydelay 4200 (was set to 30 seconds when testing)

autopoweroff 0 (not sure if that's necessary as it doesn't seem to apply to battery mode.)

AC mode:

hibernatemode 0 (I don't want hibernate when I'm plugged in.)

autopoweroff 0

standby 0 (not sure if that's necessary as it doesn't seem to apply to AC mode.)

I saw a discussion where some people were complaining about the computer coming out of sleep or hibernate mode when plugging or unplugging the computer even if acwake was set to 0. It seems that the computer is waking up briefly to adjust to that change of state. What I saw with the above settings was that when plugged in with the lid closed and sleeping I would unplug my MBP and it would wake up and see the change in power state and then go back to sleep and shortly thereafter hibernate (while I was testing this I had the standbydelay set to 30 seconds.) I'm not sure it would do what you wanted which is for it to acknowledge the change in power state but only write RAM to disk when the battery was low. I think what mine did when going from plugged to unplugged was wake up, see that change in power state, write RAM to disk, go to sleep, and then hibernate after the allotted time.

This is what I'm seeing and when I do a "pmset -g log" what I see in there seems to confirm this. What I'm really interested in seeing is if my computer will now hibernate after 4200 seconds when on battery and I will get vastly improved battery life. Meaning I can leave it unplugged, close the lid when done using it, and come back days later and have just about as much battery as when I left it.

Kevin

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