MacOs, Sleep-Wake, Power-Management – Fixing Aggressive Hibernate in Mountain Lion

macospower-managementsleep-wake

Recently, my MacBook Pro (mid 2012, 15 inch, 10.8.2) has started going into what seems to be hibernate mode after several hours asleep, whether it's plugged in or on battery. When I unplug it, it wakes briefly without me opening the lid (I can tell because the CD drive cycles). If I open the lid, I see it loading the hibernate file before becoming active again.

I looked at the output of pmset -g, and see the following settings that might be relevant to this problem:

lidwake              1
autopoweroff         1
autopoweroffdelay    14400
standbydelay         4200
standby              0
hibernatemode        3
acwake               0

Interestingly, "acwake" is zero, as is "standby". But "autopoweroff" is 1, and the "autopoweroffdelay" is 14400 (4 hours). Looking at the system log from last night, I see these entries:

Nov 26 22:36:28 ITHAA1STHOMAMBP kernel[0]: sleep
Nov 27 02:36:30 ITHAA1STHOMAMBP kernel[0]: Wake reason: EC.SleepTimer (SleepTimer)
Nov 27 02:36:30 ITHAA1STHOMAMBP kernel[0]: AirPort_Brcm43xx::powerChange: System Wake - Full Wake/ Dark Wake / Maintenance wake
Nov 27 02:36:30 ITHAA1STHOMAMBP kernel[0]: Previous Sleep Cause: 5
...
Nov 27 02:36:51 ITHAA1STHOMAMBP kernel[0]: hibernate_page_list_setall(preflight 0) start 0xffffff80de079000, 0xffffff80de0b9000
Nov 27 08:38:21 ITHAA1STHOMAMBP kernel[0]: hibernate_page_list_setall time: 491 ms
...
Nov 27 08:38:31 ITHAA1STHOMAMBP kernel[0]: sleep

I put the computer to sleep by closing the cover at 22:36. It woke itself 4 hours later at 02:36 and hibernated. At 08:38 I unplugged the power to bring the laptop to work, and it woke briefly.

What it looks like to me is that the computer is going into auto power down after 4 hours. But there are some things I don't understand:

Why did this start happening recently (within the last week, as far as I can recall, and not associated with any software update)?
Why does it wake on power change when "acwake" is 0?
Can I just set "autopoweroff" to 0?

Best Answer

I noticed the same. Luckily I had the free support option still active and I contacted them. See my post here at Apple Support Communities: MacBook Pro wakes from sleep at connect/disconnect AC power.

Regarding waking up when AC power is attached/detached I have contacted Apple support and they were able to reproduce the problem. They consulted the behaviour with their engineers and they said that this is the expected behaviour. I don't know what is the reasoning behind this however I was also informed that I can provide feedback (via apple.com/feedback ) and I did. If you guys think (like I do) that this feature is annoying and probably dangerous (when you detach the sleeping macbook from power and start toss it to put into backpack while hdd spins...) then I suggest to nag Apple on this matter.

Basically, they admitted that the behavior is 'not a bug but a feature.'

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Apple says the reason is to comply with the European Energy Standards. It looks like you can modify the behavior with some commandline-fu:

sudo pmset -a autopoweroffdelay 86400

will send your MacBook Pro to safe sleep after 24 hours instead of the default 4 hours.

macbook-pro – Understanding the Difference Between Autopoweroff and Standby in Power management

The autopoweroff feature is also mentioned in http://support.apple.com/kb/HT1757:

With the release of the OS X Mountain Lion v10.8.2 supplemental update 2.0, a new feature was introduced to enter safe sleep after four hours of the computer being connected to AC power. This is an effort to comply with the European Energy Standards (ErP Lot6). This will only occur if there is no wireless or Ethernet activity and no activity from external devices such as USB storage devices.

This is normal behavior for the following models:

MacBook Pro (Mid 2012 and later)

MacBook Pro (Retina, Mid 2012 and later)

MacBook Air (Mid 2012 and later)

iMac (Late 2012 and later)

Mac mini (Late 2012 and later)

Standby mode is documented in http://support.apple.com/kb/ht4392:

Macs that can use standby mode:

MacBook Pro (Retina, 13-inch, Late 2012) and later

MacBook Pro (Retina, 15-inch, Early 2013) and later

MacBook Pro (Retina, Mid 2012)

MacBook Air (Mid 2010) and later

SSD and Fusion drive versions of Mac mini (Late 2012) and later

SSD and Fusion drive versions of iMac (Late 2012) and later

Mac computers manufactured in 2013 or later enter standby after three hours of "regular" sleep. Earlier computers activate after just over an hour of "regular" sleep.

To enter standby, the computer must:

Be running on battery power (if it is a Mac notebook computer).

Have no USB devices attached.

Have no Thunderbolt devices attached.

Have no SD card inserted.

Have no external display attached.

A computer with a fully charged battery can remain in standby for up to thirty days without being plugged in to an AC power source.

The state of the computer is saved to the flash storage (SSD), then the power to the hardware subsystems turns off to increase the length of the standby. For example, RAM memory and the USB bus are powered off during the standby.

So standby mode and autopoweroff are supported by different models of Macs and they are enabled under different conditions. Standby mode was introduced in 2010 and it was initially only supported by MacBook Airs, but it is now supported by all new Macs except Mac Pros, iMacs with no SSD, and Mac minis with no SSD. autopoweroff was introduced in 2012 and it is supported by all new Macs except Mac Pros.

I don't know if the state of being in standby mode is different from the autopoweroff state. A gray screen with a progress bar is shown when a Mac wakes up from both states.

Note that Apple has used "safe sleep" to refer to both the hybrid sleep and hibernation mode that laptops use by default (like in http://support.apple.com/kb/PH11096) and to the hibernation-only state (like in the first block quote above).

Even if you set standbymode to 0 and disable standby mode and autopoweroff, you won't waste that much energy. New laptops use about 0.7-1W of energy in sleep mode and about 0.2-0.3W when off or in hibernation mode.

Best Answer

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MacBook Pro has to recover from Safe Sleep after 50% of all sleeps, although power is connected

macbook-pro – Understanding the Difference Between Autopoweroff and Standby in Power management

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