OSFMount virtual drive contents remain after PC power off

[yonizaf]

I create a virtual drive at boot (task scheduler) with this command:

OSFMount.com -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.

[David (PassMark)]

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

[yonizaf]

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

[David (PassMark)]

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.

[yonizaf]

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.

[David (PassMark)]

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

[yonizaf]

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.

[yonizaf]

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

[David (PassMark)]

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".