The problem:I was trying to get my Server 2012 R2 Essentials (Hyper-V VM) to do nightly backups of my Win 8.1 client PCs. As far as I had understood from the Microsoft presentations the server should be able to wake up the clients automatically from hibernate (I selected this option during setup of the connector). Unfortunately, Microsoft does not care about providing serious docs for their Windows / Server products. What is really annoying is that I don't even find any documentation how the wake up procedure actually works. Does it use Wake On Lan? Are there any magic packets involved? You pay a lot and get something that either does not work or does not tell you how it works.
What I had tested so far: I had setup the server to start client backups at lets say 10:00. So at 9:50 I put my client computer in hibernate and wait and wait ... but nothing happens. It is very sad to have to guess and wait multiple hours or days to see if backup actually works on a server system. I still don't know if the server uses wake on lan or sets some timer on the client computer to wake it up. If I know it uses WoL I will also check my BIOS and network adapters. But this is a nightmare how a server OS is sold without any serious docs.
The solution:Finally I found a very nice YouTube video that explains in details how the whole process works:
According to the video, the server simply schedules a task on the client PCs at some time in the range defined on the server: E.g. if I enter 11:00 - 12:00 this task seems to set a random wake-up time at e.g. 11:25 on the client PC. This task is then scheduled to wake up the PC - didn't know that this is possible.
It seems to work now. As discussed above the clients are woken up by the task set by the server in the task scheduler. This works in hibernate mode, not in shutdown. Still wondering how the server exactly schedules backups as it does not know how long a client backup will take and therefore does not know when to schedule the next PC...
In each case I am still very very disappointed and annoyed because of the lack of docs for the latest Windows Client/Server products.
IMHO Windows Server should have offered the possibility to use Wake On Lan too. This is a much nicer way to do backups. It can't be that hard for Microsoft to send out a magic packet which would also be able to wake up a client when the user has shut it down.
Here is the link to the video I talk about: http://www.youtube.com/watch?v=c6ZOWjaZpIk
BTW: Another possible problem may be some special BIOS power settings, for example on my brand new Dell PCs there is a default Deep Sleep option in the BIOS concerning states S4 and S5. When this option was turned on (default) it prevented Wake On Lan from working at all, although it was enabled in the BIOS, see e.g. here:
I first thought that Deep Sleep may be causing my wake-up problem but now according to the video above backup seems to rely on task scheduler only and not on WOL, let's see...
Hope this helps! Thank Microsoft for wasting our time so successfully!