Microsoft

How Windows 8 Hybrid Shutdown / Fast Boot feature works

Sleep, hibernate, fast boot, and hybrid shutdown are not all the same thing in Windows 8. Greg Shultz explains how it all works.

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A friend of mine recently got a new Windows 8 system and after using it for a couple of weeks sent me a list of questions that she had about some of the features in the new operating system. She also had quite a lengthy list of questions about features that she had been used to using in previous versions of Windows, which were either no longer available or changed in some way in the new version. While I was able to answer all of the questions to her satisfaction, one set of related questions stood out for me.

She asked me why the default Power menu had both Sleep and a Shut down commands, as shown in Figure A. "Aren't these operations the same thing in Windows 8 with its new Hybrid Shut/Fast Boot feature?", she asked. And, isn't Fast Boot essentially Hibernate?

Figure A

Fig A 10-25.png

By default the Power menu has Sleep and Shut down commands.

As I pondered the answers to these questions, I realized how difficult it could be to describe. I also realized how easy it is to be confused by the whole thing and thus I decided to write this article.

Overview

The goal of Fast Boot is pretty obvious from its name - Windows 8 boots up faster than previous versions of the operating system ever did. To accomplish this feat, Windows 8 doesn't totally shut down when you click the Shut down command. Instead it only partially shuts down and partially hibernates. This is the Hybrid Shutdown part of the equation. Then, when you turn on your computer, Windows 8 starts very quickly because it only has to partially boot up and partially wake up. This is the Fast Boot part of the equation. Fast Boot also gets a boost from the efficiency of today's hardware; namely UEFI (Unified Extensible Firmware Interface) and multi-core processors.

To understand how all of this works, we really have to build a foundation of knowledge. Of course, when you really dig into all the nuts and bolts of this system, it gets very technical. However, in this article, I'll just give you the basics in fairly general terms.

A cold boot operation

Let's begin with a basic understanding of how a computer boots up from a complete shut down. There are essentially three stages that a computer goes through as it boots up. When you turn on a computer, the first thing that happens is the system's firmware boots up and gets the computer hardware ready for the operating system. Next, the operating system boots up and gets everything ready for the user. Then, the user logs in and the operating system sets up the user's environment so that the user can launch applications and get to work. If we simplify these stages, we have what I'll call the hardware session, followed by the kernel session, and then the user session.

A shut down operation

As you can imagine, a shut down operation essentially works in reverse. But for the sake of being complete, let's cover it anyway. When you shut down Windows, the user session shuts down first, then the kernel session shuts down, and finally the hardware session shuts down.

A Hibernate operation

Since a big part of Fast Boot builds upon the Hibernate feature, let's take a brief look at how the Hibernate feature works. If you used the Hibernate feature in previous versions of Windows, as shown in Figure B, then you know that a system coming out of hibernation boots up faster than a system that is performing a cold boot, i.e. a system that starting up from scratch after being completely shut down.

Figure B

Fig B 10-25.png

The Hibernate command on the Shut down menus of Windows XP and Windows 7.

The reason for this is that when you hibernate your computer, the operating system doesn't really shut down. Instead, it saves the current system state and the contents of memory to a file called hiberfil.sys and then it shuts down the computer – the hardware. Later, when you turn on, or resume, the computer, rather than performing a cold boot of the entire system, the operating system reads the contents of the hiberfil.sys and then restores the system state and memory to the exact same condition they were in when the system went into hibernation. This restoration, or resume, operation can occur much faster than a computer can boot up from a complete shut down.

Of course, resuming from hibernation comes with a "your mileage may vary" clause. The reason being that the speed with which the system resumes depends on how big the hiberfil.sys file is. And the size of the hiberfil.sys depends on how many applications were running and how much data was in memory at the time that the system went into hibernation. For example, if you hibernate your system when you have Word, Excel, and PowerPoint running and files open in each application, the hiberfil.sys file is going to be larger than if you closed all your apps before you hibernate your system. If the hiberfil.sys file is larger, resuming is going to take longer. Even so, resuming from hibernation is generally faster than booting up from a complete shut down.

Knowing that people liked how fast their computers resumed up from hibernation, Microsoft decide the figure out to make the process better.

Hybrid Shutdown

Okay, now we have a good foundation with which to understand how Fast Boot works. While the name Fast Boot implies a faster startup routine, the magic actually begins at shut down using a technique Microsoft has called Hybrid Shutdown. When you select the Shut down command from Windows 8's Power menu, the first thing that happens is that the user session shuts down just like in a regular shut down operation. However, instead of closing the kernel session, Windows hibernates the kernel session. Then, the hardware session shuts down normally.

Shutting down the user session is quicker than hibernating it, which is an improvement over the old hibernation operation. And, hibernating the kernel session is quicker than shutting it down, which is an improvement over the old shutdown operation. So, these two operations combined allow Hybrid Shutdown to shut down Windows 8 faster than previous versions of Windows.

Fast boot

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When you turn on the computer, the first thing that happens is the system's firmware boots up and gets the basic computer hardware ready for the operating system. On a modern Windows 8 computer, the establishment of the hardware session is a much quicker operation than on older systems because the UEFI system is much more efficient than the BIOS system. To complete the hardware session, the operating system enumerates all available hardware and loads the appropriate drivers, thus ensuring that a solid hardware session is available.

Once the hardware session is ready, the operating system begins its resume operation. Since the resume operation consists only of restoring the kernel session, rather than restoring both the kernel session and the user session, the resume operation can occur much quicker. In addition to this, the resume operation gets a boost from the fact that the operating system is now designed to take advantage of multiple CPU cores when it comes to processing the hibernation data file. (The old resume process only used one.) If your Windows 8 system is installed on an SSD, you can expect an even more responsive resume operation.

Performing a real shut down in Windows 8

At this point my friend was wondering, if selecting the Shut down command from Windows 8's Power menu performs a hybrid shutdown, rather than a real shut down, how do you get a fresh kernel session - in other words how do you achieve a real cold boot? Well, when you click Restart you will indeed get a full reboot of the system and thus a fresh kernel session.

You can also achieve a real shut down using the Shutdown command line tool. To do so, you can open Command Prompt and type the following command:

Shutdown /s /t 0

If you want to have regular access to a real shut down procedure, you can use this command line in a shortcut.

Sleep and Hibernation modes

In Windows 8, Sleep and Hibernation work pretty much the same as they did in previous versions of Windows. Selecting the Sleep command from the Power menu, essentially pauses the operating system, puts your work and settings in memory and then puts the entire system in a low power consumption state. Pressing any key will instantly revive the system and you can get back to work right where you left off.

While it doesn't appear on the Power menu by default, you can add Hibernate from the Power Options | System Settings screen shown in Figure C. When you do, selecting the Hibernate command puts the system into hibernation mode just like I explained earlier.

Figure C

Fig C 10-25.png

You can add the Hibernate command to Windows 8's Power menu.

What's your take?

Now that you know how it works, what do you think about Windows 8's Hybrid Shutdown and Fast Boot features? As always, if you have comments or information to share about this topic, please take a moment to drop by the TechRepublic Community Forums and let us hear from you.

Also read:

About

Greg Shultz is a freelance Technical Writer. Previously, he has worked as Documentation Specialist in the software industry, a Technical Support Specialist in educational industry, and a Technical Journalist in the computer publishing industry.

34 comments
thanhduy90
thanhduy90

So Great ! It is so helpful

Thanks so much !

rdahuja
rdahuja

Does the hybrid shut down work even if you yank the power cord out from the wall electricity port in a pc ? If yes, how does the OS stay alive, even when the PC has no source of power ?

beck.joycem
beck.joycem

I wonder whether the Shut-Down-isn't-really is behind the recent spate of windows 8/8.1 machines I've seen in stubborn repair-error-reboot loops? It seems much more difficult to break into the cycle than it was with Windows 7 - two recent laptops refused to let me break in with the function key to initiate some kind of repair. Hitting the power switch, removing battery and leaving a few minutes, hitting any and every function key - it was as though the keyboard was dead, or the BIOS/UEFI/Windows Boot routine just wasn't listening. I had to detach the hard drive in one case, in order to get to the recovery stuff! The other one's still on the bench - possibly hard drive errors, but that's beside the point, I cannot break into the boot-error-reboot cycle by any means.

henry
henry

Hello Greg Schultz

I have some issues around W8 and W8.1

Gisabun
Gisabun

A bit odd to have an article on this topic a year after the ODS came out.

LarryHazen
LarryHazen

Your article was well timed!!! I was under the impression that Shut Down did just that so thanks for explaining that. 

I have had issues with 2 previous laptops in which my tech company said I had bad sectors and could not rebuild my operating system because they were damaged beyond repair....  they also mentioned that I should not transport my laptop in sleep or hibernation mode because my hard drive doesn't really shut off and moving the laptop in this mode is what damages the hard drive...

So what's the scoop can we transport laptops safely in either mode? 

Now I'm really confused and scared for transporting my brand new Samsung Win 8 machine.

inventor96
inventor96

To bad these new power features in Windows 8 aren't supported when it's installed on a VHD... Oh, well, there's disadvantages to everything.

hayakawa
hayakawa

I would like to see the CPU vendors provide on-chip storage for the OS to reside. If they can provide Level 3 cache, what's to stop them from adding 10GB of  additional storage for the OS? Only the necessary code would be loaded into the on-chip storage. The rest of the OS could reside on disk or cache. If the space was large enough in enterprise class systems, any additional space could be used as a cache to boot virtual machines out of. If SSDs are fast, just think how fast booting from on-chip storage would be.


tomi01k
tomi01k

This is terrible.  Most of the time a good shutdown is what is needed to resolve issues.  Now a cold shutdown is the equiv of a restart?  LOL Good to know.  What a mess they have made of things with Windows 8.  First of all, with the UEFI instead of BIOS we can't "upgrade" to Windows 7.  Which is what most people want as an option after using Windows 8.  

Second of all, with the problems involved with printer and device drivers and other programs we have a need for quick resolve with normal shutdown especially in troubleshooting and reaching solutions with problems. 

Now they expect us to use a command line?  Are they fricking nuts?   This sucks the big one.  Bigtime.

I just don't know what koolaid they have drinking over at MS but I can assure you they are not out in the field dealing with people and their computer problems or in an enterprise situation that requires predictable consistancy at low costs.  WTF are they thinking?

And a computer should have the option of using Windows 7 or XP which is taken away with the Windows 8 UEFI instead of a BIOS.  Is MS aware that most people realise this is a hook to keep Windows 8 installed and takes away the use of the computer for anything else?  Just too much assumption on MS that Windows 8 will gain acceptance and now we have merchants who can't give away the hardware with this UEFI instead of a BIOS.  At least to people who realise what this change means.

amj2010
amj2010

My oldie Dell Inspiron 6400 hangs in the lockscreen turns black with Windows 8.1, what's the matter here, use SSD ...........

Gigabytez69
Gigabytez69

Okay in UEFI bios just like in old BIOS there are power settings called s1 and s3. What are these modes?

My new system quite often locks itself up and the monitor will not resume from sleep mode. I don't use hibernate modes they are disabled as are sleep to try and fix this issue. Screen saver starts at 15 min and power off screen at 1 hr.

ASUS Crosshair V -z Amd 8150 8 core CPU AMD Radeon HD 7870 2gb and 16 DDR 3 1600 and windows 8 / 8.1 1tb Sata 3 drive.

amj2010
amj2010

My son told me that putting wee8 or 8.1 to hibernate with a SSD as bootup disk that is bad for the disk and unnessary, is this true? Tell me...

onapthanh
onapthanh

I know the hiberfil,sys is always the size of the installed ram.  I should be trying out using sleep I suppose - but that doesn't seem to turn off the power supply - the psu fan continues to run. Then I restart it every now and and then but it's my media server so I like it to be available when I want it@ http://onaprsc.com.vn / http://onaplioa.com.vn

gkeramidas
gkeramidas

as far as I know the hiberfil,sys is always the size of the installed ram, so having more or fewer apps running shouldn't make a difference.

Bill Prast
Bill Prast

UEFI is a royal pain for IT guys

Michael Franks
Michael Franks

Don't make a difference because I never shut my PC down, it sleeps when i sleep and wakes when i wake ;)

Torben Porsgaard
Torben Porsgaard

Great feature, and with 8.1 im actually happy with Windows.

Brian Hochmuth
Brian Hochmuth

Keeping windows 7 until windows 9 or a better version ships.

Mark W. Kaelin
Mark W. Kaelin moderator

How do you choose to shut down your Windows 8 personal computer? Did you realize the subtle differences between your choices?

david43567
david43567

@beck.joycem One of the first mods I did on my new Win8 c (and on my previous Win XP c) was to uncheck the 'reboot after error' checkbox in the c properties. Checking that box by default, which creates the possibility of an infinite loop, is such a major design flaw! If a BSOD error happens later in the c's lifetime, you want to have the chance to see what type of error happened, and even to debug the memory 'mini dump' if you want to. (Any 'impossible' error CAN actually happen when hw, malware, or MS bugs create random reads or writes or other ops.)

NeverCast
NeverCast

@LarryHazen  You can move your laptop around in either mode just fine. In Hibernation, your device is entirely powered down, removing the battery and restoring it later will cause the system to restore your session as usual. However in Sleep the system is in a low power state, the HDD (Hard Drive) is powered down and the head is docked, but your RAM is kept powered to keep your information in memory for restoration. Removing the battery and power supply of your laptop while in Sleep mode will cause your session to be lost.

ncgmcpherson
ncgmcpherson

@tomi01k  actually your comments are exactly what I'm seeing.  You'll be happy to know that I'm not a hater, but I am an alumni of Microsoft.  Overall Windows 8.1 does have a lot of good features.  However, on my new high end desktop I'm seeing similar problems after shutting down the machine will not reboot.  It's only when I use the hard reset switch that the machine boots normally.


This was very common to the early days of hibernate.  Because it saves everything in the file, sometimes on reboot things do not load in the expected order, or what was corrupted in memory before loaded corrupted again from the hibernate file.  Over the years they got it mostly working.


I am sure that the new apps eco-system, and tightly built hybrid devices work well with this new design.  However, Desktops and Laptops, which have proven are going nowhere, do not play well in this space.  Because of the applications and vast array of hardware configurations, a good, clean shutdown is needed from time to time.

ParNeverhood
ParNeverhood

@tomi01k No issues for me, and I have been using Windows 8 since the developer preview. 

midlantic
midlantic

@tomi01k you obviously haven't used WIN 8 for any meaningful period of time (if at all) and are just a hater. You post was absolutely useless. 

TuesdayNews
TuesdayNews

@amj2010 

Your son is correct. Fast startup should be disabled for SSD systems. If you leave it on you will get these “critical errors” when you shutdown.

Source: Microsoft-Windows-Kernel-Power
Event ID:41
Task Category: (63)
Level:Critical
Description:
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.

ParNeverhood
ParNeverhood

@amj2010 He is probably saying the system boots so quickly that hibernating does not serve the purpose of Fast Start like it did in the past.  Anymore on modern hardware I typically just put the system to sleep if I intend to get back to the same session I had going.  (Modern OS also, Windows 8 provides deep sleep so the hardware does not run out of power so quickly)

Bad for the SSD was true in the past, but updates to the SSD firmware has removed that concern.  i.e. you are writing over one section of the disk over and over. 



adams
adams

@amj2010 I don't see how it would be bad for the SSD, and "unnecessary" is technically true, though drawing less power when not being used is a good thing for any appliance.  The one issue SSDs can have that doesn't really affect HDDs is that the cells that store the data can only be written to so many times before they degrade (very oversimplified).  In a hibernation state, nothing is being constantly written to the disk so in theory it would actually extend its life a bit.  That being said, newer SSDs can be written to with no problems so many times that their lives are pretty much commensurate with HDDs anyway and the OS can bypass bad sectors on them just as it does on platter drives, so it's probably a moot point anyway. 

my_bit_bucket
my_bit_bucket

@gkeramidas  The size of the file is the same, but the information in the file can be of different sizes. It can be say 4GB in size and have 1GB of data and 3GB of zero-fill data, this prevents it from fragmenting the hard drive where the system files reside.  Also, the programming knows to only process the 1GB of real data, which is faster than reading the whole 4GB.

LarryHazen
LarryHazen

@Torben Porsgaard The only issue I had with Win 8.1 was it ties with IE11 (which I did not even know was out) and my software company only recently approved and wrote code for IE10....  I had to go back to Win 8 which was not really bad considering most all my programs were still there even if it said it would not.  Yes I had updates to do but it really wasn't that bad either.

Gisabun
Gisabun

@Brian Hochmuth : Errr. You think "Win 9" will have Microsoft go back to something like Windows 7? Keep dreaming.

pethers
pethers

@Mark W. Kaelin I leave my desktop running all the time... LOL not very power efficient. I restart it every now and and then but it's my media server so I like it to be available when I want it.
I should be trying out using sleep I suppose - but that doesn't seem to turn off the power supply - the psu fan continues to run? There must be newer systems out there that have more efficient PSU's now so more power can be saved with sleep.

david43567
david43567

@pethers If your c draws 70 w when running, and the cpu fan draws 1 w, then the power used by the fan is not significant. You should use 'sleep' if you want to save much of that 70 w. If you want 24 hr/day access with no pausing, then keep your power 'always on'.

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