Currently, there are three Macs that can take advantage of OS X Mountain Lion’s Power Nap. If you’re one of the lucky ones, Power Nap can do some amazing things.
The idea behind Power Nap is that there are all kinds of things that may be happening while your Mac is snoozing. You may have new email, iCloud may want to update your contacts, and so on. If the Mac waits until you wake it from sleep, there could well be a flurry of activity that could slow you down, so it’s really best to have some things happen even while the big cat sleeps.
Here are the Macs that currently support Power Nap:
- MacBook Air (mid 2011)
- MacBook Air (mid 2012)
- MacBook Pro (Retina, mid 2012)
Even after you install Mountain Lion, you’ll still have to apply a firmware update to enable Power Nap. Look for that in System Preferences -> Software Update. In Mountain Lion, that will take you to the Mac App Store.
What Power Nap Can Do
According to Apple’s Knowledge Base article, these actions can take place when your Mac is sleeping, even on battery power.
- Mail. Receive new messages.
- Contacts. Your Contacts update with any changes you may have made on another device.
- Calendar. Receive new invitations and calendar updates.
- Reminders. Reminders updates with any changes you may have made on another device.
- Notes. Notes updates with any changes you may have made on another device.
- Documents in your iCloud account. iCloud pushes any edits you made to a document to your Mac notebook.
- Photo Stream. Your Photo Stream updates with new photos from your iPhone, iPad, or iPod touch.
- Mac App Store updates. Your Mac notebook can download updates from the Mac App Store.
- Find My Mac. Locate a lost Mac notebook even when it’s sleeping.
- VPN on demand. Corporate email updates securely.
- Macs in managed environments can receive configuration profile updates.
If your Mac is connected to power, these additional actions can take place while sleeping.
- Download software updates
- Make backups with Time Machine
- Perform Spotlight indexing
- Continue Mac App Store downloads.
- Update Help Center.
Defaults
After you upgrade to Mountain Lion, Power Nap will be off by default when on battery power. You can change this in System Preferences -> Energy Saver.
After you upgrade to Mountain Lion, Power Nap will be on by default when connected to a power adapter. You can change this in System Preferences -> Energy Saver.
Issues
Battery Life: If you have Power Nap turned on while on battery power, and the battery level reaches 30 percent of capacity, Power Nap will be suspended.
Security; There is an eternal tension between the concept of convenience and vigilance. Some users may want their Mac to do all this work while it’s sleeping so that everything is up to date when the Mac is awakened. It’s ready to go. Others may feel that they’re losing some oversight and control of what’s happening and may wish to turn off Power Nap in all modes.
Time Machine: Some users have reported problems with Time Machine backups not happening with Power Nap. One way to test this is to note, in System Preferences, when the next Time Machine backup is scheduled to occur. Make sure the power is connected, then put the Mac to sleep. Afterwards, check the Time Machine Preferences panel to see if the backup actually occurred. I did that, and TM backups happened as expected.
The Future: It’s not known whether this technology will be extended to future Macs. Of course, we hope it will be.
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Sleeping Mountain Lion credit: Shutterstock
