Change in sleep behaviour on MacBook Pro and ignoring settings on Yosemite Recently (possibly since the 10.10.5 upgrade, but not sure) my MacBook Pro mid 2012 (non-retina) changed its sleeping behavior and I cannot seem to restore it. For years, I used a 48 hour hibernate delay (autopoweroffdelay). So when I close the lid or the sleep timer kicks in, my MBP would sleep (i.e. suspend to RAM) and pulse the Sleep Indicator Light (SIL) for 48 hours.

But recently my Mac will wake after approximately 1 hour of sleep and go into another sleep mode. I believe it is standby, because the SIL will turn off, but when I open the lid it takes only slightly longer than after the regular sleep state. In hibernate / autopoweroff it would take a while to load the RAM content back from the disk (which is not the case here). This does not happen when a USB disk is connected.

Here comes my pmset -g:

Active Profiles:
Battery Power       -1
AC Power        -1*
Currently in use:
 standbydelay         172800
 standby              1
 womp                 0
 halfdim              1
 hibernatefile        /var/vm/sleepimage
 gpuswitch            2
 sms                  1
 networkoversleep     0
 disksleep            0
 sleep                10
 autopoweroffdelay    2880
 hibernatemode        0
 autopoweroff         1
 ttyskeepawake        1
 displaysleep         10
 acwake               0
 lidwake              1


So my questions are:


Have you heard about any recent sleep-related changes in OS X Yosemite? How come my Mac suddenly ignores its settings?
What standby state am I dealing with? See my guess above.
And of course, how to make my settings work again?


What I tried so far (will update):


SMC &amp; NVRAM reset
Onyx maintenance
Set all timers anew, e.g. sudo pmset -a autopoweroffdelay 2880, etc.
Change hibernatemode to 3 as suggested by @rewozz
I can't tell why you Mac wakes up, but here is how you could find out:

Type pmset -b -g assertions in your terminal. That will list the drivers that have requested power setting overrides when running on battery.

You can also inspect the power management log, using pmset -g log.

For example, on my 10.10.5 MacBook Pro 2015, I found out that leaving my Sandisk Ultra fit USB3 memory stick plugged in makes my Mac wake up every 3 hours. Here's why:

$ pmset -b -g assertions
2015-10-19 18:38:32 +0200 
Assertion status system-wide:
   BackgroundTask                 0
   ApplePushServiceTask           0
   UserIsActive                   0
   PreventUserIdleDisplaySleep    0
   PreventSystemSleep             0
   ExternalMedia                  1
   PreventUserIdleSystemSleep     0
   NetworkClientActive            0
Listed by owning process:
   pid 51(powerd): [0x000000040008012e] 03:37:52 ExternalMedia named: "com.apple.powermanagement.externalmediamounted" 


ExternalMedia is set to 1 by process powerd. 

Unfortunately I haven't found out yet how to prevent this. I looked for a "com.apple.powermanagement.externalmediamounted" plist file but could not find any... So I don't know if these driver overrides can be changed or disabled. :(  Anyway, I expect it is driver dependent, so changing the behavior should also be driver dependent...

This detailed web page seems to indicate that, for external media altering sleep behavior, the only option is to unmount or eject the external media. Based on the driver the external media uses, eject is sometime required while for other unmount is enought.