Can virtual disks be resized in Windows Server 2012 R2? What do I need to know to resize virtual disks?
Yes, Windows Server 2012 R2 includes the capability to resize virtual disks (e.g., VHDX files) while the related virtual machine is actually running and virtual disk data is moving. This eliminates the need for administrators to shut down the VM first before resizing the virtual disk. The result is faster storage maintenance with less disruption to virtualized workloads.
There are a few requirements for resizing virtual disks. For example, only administrators with access to virtualization-capable servers with the Hyper-V role installed can resize virtual disks. In addition, resizing can only be accomplished with VHDX files residing on SCSI disks and controllers, so resizing is unavailable for earlier VHD files running on older IDE or other disk controller hardware.
The actual process of expanding or shrinking a virtual disk can be a bit convoluted and will require the use of Disk Manager (though the same tasks can also be accomplished through Windows PowerShell). For example, expanding a virtual disk involves the creation of a new volume that the original virtual disk is expanded into using the Extend Volume Wizard. Conversely, shrinking a virtual disk first requires using Disk Manager to shrink the volume, then reducing the size of the virtual disk as a separate step.
IT professionals who plan on resizing virtual disks should test the functionality in a lab environment using equipment similar to the production environment. This will allow IT staff to gain expertise with resizing procedures and reveal any potential limitations or roadblocks before actually rolling out the capability to production.
Virtual machines depend on the creation and maintenance of virtual disks, which are vital during boot and during routine maintenance of the image file. Windows Server 2012 R2 expands on the capabilities of virtual disks using a standardized VHDX format, allowing far larger file sizes, performance enhancements and real-time resizing without the need to stop and restart VMs. Server administrators should understand these emerging improvements and their impact on workload availability within the enterprise.
This was first published in November 2013