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OSFMount virtual drive contents remain after PC power off

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  • OSFMount virtual drive contents remain after PC power off

    I create a virtual drive at boot (task scheduler) with this command:
    Code: -a -t vm -s 1G -o format:ntfs:"ramdrive" -m "R:"
    Sometimes (but not always), after a full power off of the system (not just reboot), when I turn the system on again the previous contents of the virtual drive are still there.

    How and why does it happen? are the drive contents saved anywhere?

    Thanks in advance.

  • #2
    I think it is impossible.
    Maybe the machine was just going to sleep / hibernation and not doing a full power cycle?


    • #3
      I'm pretty sure I did power off and not hibernation. In addition, the machine was physically disconnected from power for 24+ hours.


      • #4
        Windows hibernation (and Hybrid sleep) writes the memory contents to disk, in a file called, Hiberfil.sys, which is normally hidden.
        It's purpose in life is to store the memory contents across power off situations.


        • #5
          When resuming after hibernation, the open apps stay open, and startup apps that I previously closed don't start up again. It is hard to confuse shutdown (where my apps close) with hibernation.

          I am positive that I did shut down my system, and disconnected it from power, and the files stayed in the ram drive. How it happened, I'm not sure, but I know it's not hibernation.


          • #6
            Well it is an easy test.
            Create the RAM drive. Turn off the power at the wall. Wait 10sec. Boot the system.


            • #7
              If you mean I should pull the plug while the system is running, that's a terrible test. Even the contents of my normal drives are not guaranteed to survive that.

              If you simply meant I should shut down normally and then pull the plug, that's exactly what I did. multiple times. I could do it again if you want. Then again, if you don't believe the results because they're 'impossible' and you didn't see it yourself, me testing again would not change a thing.


              • #8
                As it turns out, it was Windows Fast Startup that caused it. Apparently that 'feature' behaves kind of like hibernate, though not exactly.


                • #9
                  Yes, Fast startup writes a hibernation file.
                  I think the difference with a normal hibernation is that most Apps are closed before writing the hibernation file for normal hibernation.
                  Fast startup just hibernates the operating system kernel memory.
                  But OSFMount need to runs a kernel device driver to emulates a hard drive. So it gets hibernated along with the rest of Windows, when saving details for "Fast startup".