Root into a virtual machine (KVM)

Scenario: I have a KVM virtualization server with a number of VMs defined. Suddenly, I cannot log in as root to one of the VMs. I will need to reset the root password. The "normal" methods like adding single or init=/bin/bash to the kernel boot line in GRUB do not work. The only option left is to boot from a rescue disc, but this is a virtual machine -- there is no DVD drive. Oh, no -- what to do?

NEWS FLASH: I just learned from a colleague that there is a much easier method. It is possible to chroot directly into the VM from the virtualization host. Will post detailed instructions as soon as I get them. Until then, there is always the "long route" described below.

tune2fs: to fsck, or not to fsck?

The questions of whether to run fsck on the root filesystem at boot, and how often, are important ones for administrators. Here's some minimal information to get started:

How to mount VirtualBox VDI image in Linux

OK, how _do_ you mount a VirtualBox VDI image in Linux?

Well, here's how Jeff Waugh does it, anyway.