Virtualisation topics are coming up a lot in other threads (no wonder, seeing as it's dominating a lot of IT in general at the moment). While positive, they invariably dominate the threads and take them off topic. So this thread is aimed at keeping it all in one place. Bring all your questions into this thread and we'll nut out your nastiest virtualisation problems. I'll invariably try to change everyone over to KVM, but don't let that stop you posting questions about other hypervisors and virtualisation systems. (Extra points for the first person to say they're running bochs in production ). Hijacking from another thread: As mentioned, outside of the realm of KVM (or other hypervisors in general), but minimum disk sizes are important to know for virtualisation, as generally you're trying to keep things as small as possible. With a quality OS, you should have access to things like LVM (Logical Volume Manager) that allow you to span your OS easily over extra drives should you wish to add them later, or at the very least decent tools like resize2fs that allow you to repartition and resize your install easily. Some legacy OSes won't allow this, so it's important to pick the right size. Speaking for myself, 10GB is a minimum disk size I'll give to WinXP. For Windows 7 64bit, Microsoft recommend 20GB. I'd put down 30GB for some room to grow. For Win2K8 R2 64bit Server, Microsoft recommend 32GB minimum. I don't roll them out under 50GB on the C: drive. It ultimately all boils down to what you do with the VM when built, of course. With that said, for "appliance" style Linux boxes, I frequently get away with as little as 2GB for some installs. I average 5-10GB for most others. If I have a large app or heaps of static content to server, that always goes on a second virtual disk not attached to the main system directories or disks. Also, I'm in the process of building a 2-node "mini cluster" KVM setup for a friend, running GlusterFS to mirror disk images between nodes, and allow live migration and a relatively good level of failure recovery between the nodes. It isn't true HA (although VMWare call this HA, and they call HA "Fault Tolerance", but they're idiots), but it's nice and easy to maintain for a 2-node setup. Once done, I'll share some of the install notes here if other people want to experiment.