Mac wakes up from sleep every two hours on Mac OS X Yosemite Since upgrading to the first stable release of Mac OS X Yosemite a few days ago, my Mac Mini wakes up roughly every two hours from sleep for about a minute, then goes back to sleep. This is particularly annoying at night since I sleep my Mac, and it's in the bedroom, so I notice when it turns on.

In my Console, here's some of the lines from it from when it wakes up:

14/10/19 6:48:06.000 am kernel[0]: Wake reason: RTC (Alarm)
14/10/19 6:48:06.000 am kernel[0]: RTC: Maintenance 2014/10/19 10:48:06, sleep 2014/10/19 09:00:12
14/10/19 6:48:06.001 am SyncServer[910]: [0x7fdd69c19d80] |SyncServer|Warning| Refreshing watchdog because of a calendar time change alert.
14/10/19 6:48:06.000 am kernel[0]: Previous sleep cause: 5
14/10/19 6:48:06.000 am kernel[0]: AppleThunderboltNHIType2::prePCIWake - power up complete - took 1 us
14/10/19 6:48:06.000 am kernel[0]: The USB device USB 3.0 HUB (Port 1 of Hub at 0x15000000) may have caused a wake by issuing a remote wakeup (1)


From the last line, yes, I've got a USB 3 hub plugged in to my USB 3 port on the Mac. But there are no devices plugged into the hub. Nevertheless, I'll try unplugging it tonight, but I suspect it won't make a difference.

Also, I've already disabled "Wake from network access", disabled "Power Nap", and pretty much disabled everything else in the "Energy Saver" system preferences pane.

When I run pmset -g, I get:

Active Profiles:
AC Power    -1*
Currently in use:
 standby              1
 Sleep On Power Button 1
 womp                 0
 autorestart          0
 hibernatefile        /var/vm/sleepimage
 darkwakes            0
 networkoversleep     0
 disksleep            0
 sleep                0 (sleep prevented by iMovie, coreaudiod, iTunes, AddressBookSour)
 autopoweroffdelay    14400
 hibernatemode        0
 autopoweroff         1
 ttyskeepawake        1
 displaysleep         60
 standbydelay         4200




I often have wake problems with my Mac, especially after upgrading to a new OS, and this time is no exception:


OS X Mavericks wakes my Mac from sleep every hour or so
Mac wakes up from sleep every night and then goes back to sleep immediately
Since com.apple.mDNSResponder.plist got replaced by com.apple.discoveryd.plist after Yosemite Beta, there is another solution for your Problem.

All you have to do is to run following command in your terminal:

sudo /usr/libexec/PlistBuddy -c "Add :ProgramArguments: string --no-multicast" \ 
         /System/Library/LaunchDaemons/com.apple.discoveryd.plist    


And reboot your system and it should be gone.

Like also described here: http://ispire.me/fix-yosemite-rtc-alarm-wakeup-issue/

You just have to know that services relying on multicast might not work properly anymore after this change.