Windows 8 Fast Startup dangerous for dual boot systems

J65nko

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An article at h-online.com warns users of dual boot systems with Windows 8 Fast Startup that they risk data loss:

The Fast Startup feature creates an issue because it doesn't shut Windows 8 down completely but switches it to a special hibernation state instead – although it looks like it has been freshly booted when switched back on because all applications have been closed. However, for the Fast Startup feature's hibernation state, Windows 8 will store Windows session information – such as the cache with the current filesystem state of any mounted FAT and NTFS partitions – in a memory image that is restored during Fast Startup.

This can easily cause data loss when other operating systems are used to write to these partitions: after waking up, the supposedly powered-down, but actually hibernating, Windows will resume operation with now obsolete data and filesystem information. The risk exists not only when Linux is installed on disk in parallel, it also arises with any other type of access – such as that from the Windows-7-based Windows PE 3.0 or from recovery systems that are booted from a CD or USB flash drive.
 

tingo

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But only if you allow Windows 8 to use / touch filesystems / partitions that belong to other operating systems...
 

phoenix

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No. If you enable "Fast Startup", Windows 8 leaves all the filesystems mounted, writes out filesystem, memory, and app state to a hibernation file, sets a flag in the filesystem, and then goes into sleep/hibernation mode.

If you then boot a non-Windows OS, mount the NTFS partition, and try to write to it, bad things happen when you next load Windows 8.

This has nothing to do with Windows 8 writing to non-Windows filesystems.
 

tingo

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Of course it could do bad things to Windows own partitions. And you should know that.
 

usdmatt

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And you should know that.

Most users would, quite reasonably, expect to be able to mount an NTFS or FAT file system from a powered off Windows machine on another OS. Lots of people do this in order to share files between multiple operating systems.

The problem mentioned here is that Windows keeps the file system mounted and all state data intact when using Fast Startup/Hibernation. Windows just assumes that nothing has changed since it last powered off and so can quite easily corrupt anything that was changed/added.

Basically the advice is that if you want to access a Windows file system from another OS you need to make sure the Windows OS is shutdown fully which won't be obvious to most. I'm sure a lot of people (myself included) could quite easily turn off Windows 8 without realising it's using Fast Startup and mount the disk somewhere else expecting it to be ok if we weren't told otherwise, hence the warning.
 

Martillo1

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But if you reboot from W8, the usual shutdown is used, and you should not have problems. Am I right?
 

throAU

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phoenix said:
If you then boot a non-Windows OS, mount the NTFS partition, and try to write to it, bad things happen when you next load Windows 8.

Writing to NTFS from alternative operating systems has always been a bit dicey IMHO and should not be done if you can avoid it (by using a NAS, external drive, etc.). Whether it's Windows 8 or Windows NT 4.

Yes, this is a new level of risk, but IMHO you should already avoid doing that sort of thing. Mount the filesystem(s) read only from the other OS sure, but read-write is just asking for a world of hurt when Microsoft make some tweak to NTFS in a service pack (as they have in the past), irrespective of fast boot.
 

grahamperrin

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This subject has cropped up many times over the years, for example:

… thank you for your help ralphbsz you beautiful son of a beastie.

In order to properly shutdown Windows, there is a configuration option in the Power Settings to shutdown without a fast startup. …

  • includes a link to another ASUS page, about disabling Fast Startup in BIOS
– and so on. The originally mentioned article, in the Wayback Machine: <https://web.archive.org/web/2013011...8-Fast-Startup-puts-data-at-risk-1780640.html>.



Now, it's worth adding some links to Microsoft documentation:



Visually, from How to turn on or off fast startup in Windows 10/8.1 - Lenovo Support GT:

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