I'm using Ubuntu 12, and during installation I have chosen to encrypt the disk and home directory.
I only introduce the disk password the first time I log in, so I guess the disk is not encrypted when I lock the screen.
But what about home directory? Is it encrypted while the screen is locked?
I'm thinking that when I'm running this inside a VM (with its screen locked), someone with access to the host machine (not the VM) could access the VM's disk because it's just a file in the host machine, right? And since the VM is running, it's not encrypted, and the attacker doesn't even need to unlock the screen.
So then I thought, what would happen if I were running this as a host (not a VM), with the screen locked, and someone unplugged the disk? Would it stay unencrypted? That way the attacker doesn't even need to scan the ram looking for the key.