Microsoft streamlined the VM import process in Windows Server 2012 Hyper-V. For those familiar with importing and exporting VMs in previous Hyper-V versions, the new procedure is a welcome change.
There are several reasons why the virtual machine (VM) import process left a lot to be desired. For starters, you had to export VMs before importing them. This concept probably seems logical, but exporting VMs made the process unnecessarily restrictive.
For example, suppose a Hyper-V server's system drive dies, but the storage array -- which contains all of the virtual machines -- remains intact. In this scenario, you can't replace the failed drive, install Hyper-V and then import the virtual machines from the data drive. Because you didn't originally export the VMs, you cannot import them into a new Hyper-V installation. Instead, you have to work through a much more involved recovery process.
The anatomy of a virtual machine is another reason why the import process was often challenging. While it is easy to copy a virtual hard disk from one server to another, Hyper-V stores several VM components outside of the virtual hard disk, including the following:
- VM snapshots
- saved states
- the virtual machine configuration file
Oftentimes, Hyper-V had trouble importing these components for various reasons. For example, the VM import process often loses the virtual machine's network configuration because of the way the configuration file references the virtual network switch.
The revamped VM import process
Microsoft will introduce a number of changes in Windows Server 2012 Hyper-V to ease the VM import process.
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To start, you will no longer need to export virtual machines. Instead, you would be able to point the import wizard at a set of VM files, and the wizard will register those files with Hyper-V as a virtual machine. Because it improves on VM portability, this ability should be especially helpful in lab environments. For instance, IT pros can import VMs from a USB flash drive and use them on a temporary basis.
But the most visible changes will be in the brand-new import wizard. Unlike its predecessor, this wizard does not attempt to blindly import virtual machines. Instead, Microsoft has built intelligence into the wizard; it will check for common problems that complicate a VM import, such as virtual machine paths or incompatible hardware. In some cases, the wizard can resolve the issue automatically. Other times, the process will require manual intervention, and the wizard will walk IT pros through the proper steps. According to Microsoft, the wizard will check for and attempt to resolve more than 40 issues.
To make the VM import process more reliable, the wizard will perform five steps:
- It will create a copy of the virtual machine configuration file to guard against unexpected reboots or power outages.
- The wizard will validate the hardware: it will compare the new server's hardware against the original host's hardware and check for discrepancies that could affect the virtual machine.
- It will compile a list of errors that must be reconciled before the completion of the VM import.
- The wizard will help the administrator reconcile the process.
- It will remove the temporary copy of the virtual machine configuration file; at this point, the VM import is complete.
These improvements should greatly ease the VM import process. In addition, Microsoft is also introducing a number of Hyper-V-specific PowerShell cmdlets so IT pros can perform bulk imports from the command line.