With the introduction of XenServer 5.6, the Disk Image Import Wizard now offers all of us a bit of freedom from the hypervisor sprawl that permeates enterprise and non-enterprise virtual machine users everywhere. We’ve all been there; two, three sometimes four different hypervisors and their proprietary virtual disk formats scattered about our labs and data centers. Managing these variations fits the metaphor of herding cats and often requires paying yearly maintenance fees for support or running an aging hypervisor(s) without up-to-date security patches and bug fixes.
Now, you can leverage your legacy VMs and reduce the unnecessary support and risk overhead and sprawl by importing them into XenServer 5.6 via the Disk Image Import Wizard. This feature offers quite the bounty supporting four virtual disk and file formats: .vhd, .vmdk, .vdi and .wim.
The wizard aims to simplify the import process by requesting the user input virtual device settings for the VM and select to run an optional fixup at first boot. The process is pretty simple, but there are requirements that we need to adhere to and it is best to first understand the machine being imported. For example, many operating systems do not detect hardware changes during boot. This prevents the imported VM from loading the operating system after moving it to a different hypervisor. Another issue includes the non-XenServer hypervisor tools from the legacy VM executing after importing to XenServer. To mitigate these issues, the fixup option is often required (for more details on fixup, see Knowledge Center article CTX124961). It is also very helpful to know what is being imported with regards to the operating system and the number of CPUs. Some operating system kernels cannot easily go from single to multi-CPU and when importing a disk image, it is best practice to respect the guests current number of CPUs when inputting that setting via the wizard.
We also want to ensure that we’re importing into a Storage Repository with enough space for the virtual disk as well as a XenServer host with enough memory to boot the imported system supporting the fixup process. When we run fixups, it is an automatic process and the VM will power on with the memory settings we supply to the wizard. Our host must have the available memory to power on the VM during this process. Often we see people with a 4GB host try to importing a VM requiring 2 GB, yet the host is already running other VMs and does not have the 2 GB necessary will result in a failure with the fixup process. The fixup powers on the VM using the settings we supply in the Wizard. (See Knowledge Center article CTX125120 for info on how to resolve this problem).
Ensuring that we’re meeting the requirements of the wizard, we’re able to easily import our legacy VMs and therefore reduce or in many cases eliminate the burden of scattered hypervisors and their associated virtual disks in our labs and data centers. We can now freely employ state of the art hypervisor technology via XenServer 5.6 and still retain access to the VM workloads that required us to keep the legacy hypervisor around in the first place.
The Disk Image Import Wizard is a work in progress. Please contribute your experience (good and bad) and bring any issues you have to the XenServer Forum so we can help out. Also, check out the below video to get an idea of how easy it is to migrate into XenServer 5.6.