more graceful shutdown of VirtualBox jail

[Robert Trevellyan]

The VirtualBox jail is a wonderful thing, but more than once I've forgotten to shut down a running VM when restarting my FreeNAS box (e.g. when doing a System Update). Is there any chance the VirtualBox jail could attempt to do a Save State or ACPI Shutdown of any running VMs when it gets shut down?

 

[cyberjock]

I tried to do a "save state" type function, but the problem is that if it takes too long then the shutdown sequence kills the process due to the timeout anyway. So unless you have a VM that is very small (think less than 1GB of RAM, etc.) you'll end up with incompletely saved save states. ACPI shutdowns come with the same perils.

There also is no direct mechanism to tell a process inside the jail to shutdown before the jail receives the shutdown message. So you have technical limitations that I would likely never have been able to overcome without reworking the shutdown code (and that's not something that really should be touched).

 

[Robert Trevellyan]

I figured it would be non-trivial. As it happens my VMs are less than 1GB of RAM (just little Ubuntu servers for website development), but I realize one use case doesn't make a solution.

I haven't lost any data yet, just ended up with aborted VMs.

Very useful jail anyway, thanks!