31 December 2012

Wake-on-LAN (WOL) in Windows 8

What is WOL?
WOL feature wakes a computer from a low power state when a network adapter detects a WOL event (Ethernet packet).
I have used WOL feature for a long time. It is nice feature if you want to start your computer over the network (or internet). After installing Windows 8 I noticed that WOL doesn't work. What is wrong with WOL on Windows 8?

Microsoft changed the behavior of Shutdown procedure in Windows 8. Now network adapter don't accept WOL events after Shutdown, because Shutdown now means "zero power consumption and battery drain" (quote from Microsoft). This means that Shutdown is now real Switch off.
Solution
If you want to use WOL feature, you now need to use Sleep or Hibernate.

Sleep mode
Computer shuts down most components, but leaves some power going to keep the main memory powered.
Pros: Goes into sleep mode fast. Comes out fast
Cons: Uses up a small amount of power. If the battery dies (or is removed), all data in memory will be lost.

Hibernate mode
Computer saves the contents of memory to disk (file is called "hiberfil.sys"), and then turns itself off completely.
Pros: Uses no power, so computer can lose all power and will still recover. User has all programs and settings untouched.
Cons: Slow to go into Hibernate mode. Slow to come out.

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