Execution state is lost - only with differencing disks

[Roland Kenimer]

Basically, if I shut down the machine, then start it again, all changes which should have been written to disk are lost. This does not apply to reboots, or to saved states. If I shut the machine down, then take a snapshot, the changes are saved as expected. T

This is occurring on a Windows 7 x64 host, and Windows XP guests. I believe that the problem is not limited to XP guests. This occurs only when using differencing disks, regular disks are not affected as such.

Please see [url]​http://forums.virtualbox.org/viewtopic.php?f=7&t=26848&p=121030[/url] for details, my posts are from "rjk"

Attached are four logs: the first two are the most recent from one VM that was in a saved state when the logs were collected, the next two are from a different VM that was running when they were collected.

[Roland Kenimer]

First machine saved state log

[Roland Kenimer]

First machine next oldest log

[Roland Kenimer]

second machine running log

[Roland Kenimer]

second machine next oldest log

[Sander van Leeuwen]

The last question by Mark Cranness in the topic is a valid one.

[Roland Kenimer]

It seems that my impression of immutable disks was inaccurate: My understanding of an immutable disk was that the base image would never be written to, and all changes would go to a differencing VDI, and that was it. However it seems that the VBox developers put a nice little plot twist in, and each time the VM is stopped, the handy little differencing disk would be deleted.

Can I change this behavior without wiping out my installs? Or am I forever doomed to create a new snapshot every time I shut the machine down?

I would like to turn this ticket into a feature request: I would like to have the immutable disk functionality, (I.E., one base image) but without the auto-deletion of the VDI, so all changes [i]to the differencing VDI'si would not be discarded. Adding this as a nice little GUI button would be a bonus too. As I understand from further reading, this is already possible, if the base VDI is prepared correctly, but it is too late for me now, as I am already running with an immutable disk. Since it seems to be already possible, the GUI button would just be a series of cmdline operations.

I am aware that this could have severe disk performance implications for guest machines, but sometimes this doesn't matter a whole lot.

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.