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Why is everybody keep mentioning to disable Fast Boot on Windows 8 if you have installed alongside Ubuntu? Is it something that is recommended only for UEFI machines or is it a suggestion for Legacy BIOS machines as well? Is it because it makes the Windows partition inaccessible from Linux or there is another more serious reason to disable it?

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2 Answers 2

up vote 36 down vote accepted

Fast boot explained with an image:

Windows 8 Fast Startup vs Cold Boot

During fast boot the system loads the hiberfile and does not use the files on the filesystem.

So the biggest problem, and the worst problem you can have on a computer, is data loss: if you create a shared NTFS data partition the hibernation may maintain the file structure so if you try to save a file from Linux into the NTFS partition it will get lost on Windows reboot as it only remembers the old file structure. See this Ubuntu Forums thread for more information.

That alone is reason enough to never touch fast boot in a dual boot setup.


Two relevant discussions from Super User:

In general: if a disc is mounted when using fast boot, Windows puts this disc and its content in a hiberfile. Any changes made to the system are gone when the hiberfile is restored. This includes mounted external discs. Ubuntu will refuse to mount a disc that has a hiberfile.

One of the bad messages you see in these topics is getting a "disc has errors" when booting Windows.

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I did not understand anything in your answer. Please dumb it down a bit. –  Benjamin Hubbard Apr 21 at 15:30
    
I think what he is trying to tell is that if you are going to create and save for a example a file on a NTFS partition that you created and this partition is shared with Ubuntu and Windows, and you save this file while you are using Ubuntu then Windows will delete this file because inside the hibernation file that Windows creates in Fast Boot mode it is saved the old file structure and this one doesn't contain the new file that you created. –  underdog012 Apr 21 at 16:14
    
@Rinzwind So I guess if you don't have a shared partition is it ok to have the Fast Boot mode enabled?Eitherway Ubuntu doesn't let me access the NTFS partition that Windows is installed on. –  underdog012 Apr 21 at 16:25
    
If I have an external hard drive and I make changes to this hard drive from Ubuntu while Fast Boot is on will this problem affect the files of my external hard drive? –  underdog012 Apr 21 at 16:26
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@Rinzwind: Not at all! I think the best advice comes from the second question: "always unmount the shared partition(s) before hibernating". Only one OS should be the writer of a partition at any time, and hibernation (either by Windows or by Linux!) keeps that OS in charge. –  Jan Fabry Apr 21 at 17:45

Fast boot in Windows 8 is a way to boot the system faster because the needed data to boot (Drivers, User session, etc..) are stored in a hibernation file (hiberfile) and are loaded when the boot process begins, saving the user between 40% and more boot time.

Since Hibernation mode is a way to "freeze" whatever you were doing before shutdown and loading it again when you start the computer (this includes opened apps, sessions, drivers, the last office doc you were editing...) it creates a problem when you want to copy stuff from Ubuntu to Windows after a hibernation, or "fast boot" as it is called on Windows 8 because anything that changes between hibernating and booting again is lost.

Basically, if you shutdown Windows 8 (hibernate mode) and then go to Ubuntu and try to copy something over to Windows 8 like an mp3 file (assuming Ubuntu does not throw any warnings about it being in hibernation mode), when you boot Windows 8 again, the mp3 file will not be there because it was not frozen during the shutdown procedure you did on Windows 8 before going to Ubuntu. Since the mp3 file was not there BEFORE shutting down Windows 8, it was not saved in the hiberfile and thus will not be restored after you do a Fast boot to load Windows.

There are however 2 ways to disable this so you can share files between both systems as described in Installing Ubuntu on a Pre-Installed Windows 8 (64-bit) System (UEFI Supported)

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