For a myriad of reasons, I have been looking at alternatives to VMware ESXi for a few months. Virtualizing a few machines here and there has proven educational. Learning the ropes of working with qemu/kvm, libvirt, and virsh has been challenging at times, but overall a pleasure to work with. Working with kvm is great although it takes some getting use to coming from a VMware/ESXi centric environment.
Up to this point all of the virtual machines that I had worked with were new systems. After some research and a few backups of my current VMs running on one of my ESXi hosts, I decided to migrate a few production VMs. Here are the steps that I used to move virtual machines over from a licensed vSphere 4.1 installation to a Linux host running qemu/kvm.
For starters, be sure that you have full backups of any VMs that you plan on working with. With that out of the way, you are ready to start:
1. Remove all snapshots from the virtual machine across all virtual disks.
2. Uninstall VMware Tools and then perform a clean shutdown of the guest operating system.
3. Copy the virtual hard disk(s) over to the qemu/kvm host. The virtual disk is typically the largest file within a VM’s directory and will usually be named something like ‘guestname-flat.vmdk’
4. On the qemu/kvm host, change to the directory containing the .vmdk file. Assuming you are using qcow2 disk images, run the following command to convert the .vmdk: kvm-img convert -O qcow2 guestname-flat.vmdk newguestname.qcow2
5. Create a new VM on the qemu/kvm host and choose the recently converted disk image as your existing drive/image. It is important that you create your new guest with the same or similar settings as it had before. I recommend cloning the MAC address over to the new guest for added simplicity with NIC detection, assignment, and third party software licensing.
6. Attempt to boot the system. Depending upon your guests virtual disk settings and other factors, the system may hang during boot. Edit your virtual machine and set the controller type to SCSI assuming that was the controller type back on ESXi.
At this point your system should be up and running on the new host. I did find notes and suggestions that qemu/kvm can run vmdk files/disk images, but there seemed to be a handful of caveats so I decided to convert the vmdk’s over to a native format.