VM Live Mode: Immutable Disk Method on VirtualBox
|About this VM Live Mode/Immutable Disk Method on VirtualBox Page|
For VirtualBox there is also an alternate way to set the disks to read-only.
This option is the official way for setting VM's to read-only in VirtualBox. This option will also only work with the
grub-live package, which is installed by default. 
This option will not work with the
- VirtualBox implements hard disk write protection differently. If an immutable virtual machine is booted, VirtualBox will always create a snapshot where data is written. After shutting down and booting the VM again (a soft reboot is inadequate) the old snapshot will be deleted and a new one created. The consequence is that data will not persist in the VM, even if Live-mode is not selected. However, since the data is written to the hard disk of the host (instead of memory), it is easily recovered. Therefore, it is necessary to select Live-mode to be safe. A snapshot file is still created, but it will not store any altered content from the VM.