macOS Sierra on external drive – Mac do not go to sleep anymore Since two days I am using an external SSD as system disk (to work with my system on my iMac or on my new arriving MacBook Pro – on demand – without any synchronization process). Just attach the disk and boot my system.

On my iMac this work pretty good. I have tested my Thunderbold 2 case – wich was faster on boot as the USB 3.0 case. But the Thunderbold case need external power – so thats not perfect.

Now I am using the USB 3.0 case just connected via USB. And this morning I noticed, that my iMac didn't went to sleep – just the dispay turned off. So the system will not go to sleep automatically. After 5 minutes with turned off display I can still see some flashing LED on the SSD case – once a minute or something.

What can I do to get my system automatically to sleep again?



Update:  

Running pmset -g in Terminal, I get the following

Currently in use: 
standby               1 
Sleep On Power Button 1 
womp                  0 
halfdim               1 
hibernatefile         /var/vm/sleepimage 
powernap              0 
autorestart           0 
networkoversleep      0 
disksleep             0 
sleep                 1 (sleep prevented by backupd, backupd, UserEventAgent) 
autopoweroffdelay     28800 
hibernatemode         0 
autopoweroff          1 
ttyskeepawake         1 
displaysleep          1 
standbydelay          10800
Maybe you have "Prevent computer from sleeping..." activated in Energy Saver preferences.