Today I did quite a lot of work on my Solaris 10u7 Virtual Image. I wanted to be safe and use the screenshot functionality to save it.
I already had a screenshot done, so I just did another one:
VBoxManage snapshot JesSol10u7 take test02 -desc "this is the 2nd screenshot, testing purposes"
OK good. I then wanted to try out and see the if the screenshot worked well by restoring it: few modification on the image -> Google, "VBoxManage snapshots restore select" => http://linux.com/news/enterprise/systems-management/8224-secrets-for-controlling-virtualbox-from-the-command-line
There I found what I wanted: "With a stable snapshot in hand, go ahead and play with the system. If
you get in trouble and your machine won't boot or starts behaving
abnormally, you can revert to the snapshot of the stable machine. To do
this, first power off the VM with VBoxManage controlvm "Fedora"
poweroff, then revert to last snapshot with VBoxManage snapshot
"Fedora" discardcurrent -state. If you have multiple snapshots, you can
revert to the last but one snapshot with the -all switch instead of
Ohh, what is this "-all" option ? Going back not to the last screenshot but to the pre-last one ? Interesting... OK ! Let's give it a try, restore the 1st screenshot, and then I'll restore the 2nd one...
VBoxManage snapshot JesSol10u7 discardcurrent -all
Wrong ! At least wrong for what I wanted to do: the 1st screenshot got well restore, but the 2nd one disappeared !! Oh no, all the work I specifically saved lost ! Grrrrr...
Well, that's it, those VirtualBox screenshots do not save the state of the machine at some point, but the differences between two states. The advantage is that screenshots take less place, but you the different screenshots becomes inter-related... If you "go back" of 2 screenshots, you can not go back anymore to the screenshot you skipped... At least that's what I understood.
So just be aware of it when you're using the "-all" option !