Saved session after a power outage.

Discussions related to using VirtualBox on Linux hosts.
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dgcov
Posts: 12
Joined: 22. May 2012, 23:17

Saved session after a power outage.

Post by dgcov »

Is it possible to recover a saved session after the host has reboot?

I have a saved session which I was working on when a power outage occurred.

On reboot of the host (Debian) the Guest (Windows XP) is marked as "Powered off".

Is it possible to recover my save session?
mpack
Site Moderator
Posts: 39156
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Mostly XP

Re: Saved session after a power outage.

Post by mpack »

A saved session is by definition saved (to disk), before the VM terminates, so of course it can be recovered. It doesn't matter how many times the host is rebooted, as the host is a different PC. The saved session will exist until you start/resume the VM, or discard the saved state.

But.... if you lost power while the VM was running then you don't have a saved session. What made you think you do?

Even if you don't have a saved state, the disk drive should be in a crash consistent state with a fairly recent version of the file you were working on - assuming you weren't working for hours without saving.
dgcov
Posts: 12
Joined: 22. May 2012, 23:17

Re: Saved session after a power outage.

Post by dgcov »

The saved state had been saved previously.

I opened a Virtualbox session and then saved it. It was after the session was reopened that the power outage occurred.

I suppose I'm hoping that the saved state exists on the disc and isn't immediately overwritten on resumption of the session.
mpack
Site Moderator
Posts: 39156
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Mostly XP

Re: Saved session after a power outage.

Post by mpack »

The saved state is restored at the beginning of the next session, but when exactly it is deleted I don't know. But, if you've already run the session and either closed it or saved the session again then the old saved state is definitely gone.

Even if it existed, a saved state only preserves the contents of RAM, including disk buffers, but not the disk files themselves. The virtual drive should do a reasonable job at that. So I notice you didn't answer the question about saving your work as you went, I guess because you didn't. What was the application? Did it not have autosave?
dgcov
Posts: 12
Joined: 22. May 2012, 23:17

Re: Saved session after a power outage.

Post by dgcov »

I was working on a temporary file, that I didn't wish to keep for a number of reasons: It's a large file, for one, and I didn't want multiple versions of the same file to exist on the system and cause confusion, so when I've finished, I can leave the application and overwrite the current version if needed, or simply discard the version I don't want saved. I am aware that there are other ways of doing this: I could save in my /tmp directory which gets cleaned after reboot, for instance. However, this is not about my sloppy working practices, even if some would regard them as inept.

In this particular case, I hadn't finished working on the temporary file when the power outage occurred.
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