As most people who work with Server Virtualization realize, storage is one of the biggest components of the architecture. As VMs grow and the storage used by the Hyper-V host starts to get full, what options are available to the administrator? One “solution” could be to shut down the VM and then move the files to another storage device and then restart the VM. This will work, but you are left with downtime. The better solution would be to perform a Storage Live Migration and have no down time. Hmmm…. which one would you pick?
In Part 8 of the Server Virtualization Series, Brian Lewis details the benefits of using Storage Live Migration and walks through the process of configuring and performing a Storage Live Migration. I am including a brief snippet from Brian’s blog post below, but you will want to read the full article by visiting Brian’s Post.
This is post 8 of 20 in a series of how to’s on Virtualization with Microsoft Hyper-v. For a full list of posts in this series please see Dan Stolts’s original post (o of 20) located here:
Storage Live Migration:
In Windows Server 2012 and the free Hyper-v Server 2012 Microsoft engineers added the ability to move the storage of your virtual machine while your VM is up and running. For those of you who use VMware, Microsoft storage live migration is like VMware storage vMotion.
This means you can move the virtual hard disks used by a virtual machine to different physical storage while the virtual machine remains running. You heard right – it is not necessary to take a virtual machine offline to move the VMs files to different physical storage.
Storage Live Migration is supported for both VHD and VHDX file types. In Server 2012 VHDX is the new virtual hard drive format that uses a 64k block size to support virtual disks up to 64 TB in size. The old VHD disks use a 512 byte block size and have a max size of 2 TB. These new VHDX files also offer improved disk access speed than the old VHD file format.
The most obvious benefit is the agility of moving or upgrading your backend physical storage without having any VM downtime. The Virtual Machine disk is mirrored to either a local disk or shared storage point where the server can continue to run the VM. Once mirror process is complete, Hyper-V switches the VM to run from destination virtual hard disk. In the case where Hyper-v fails to be able to use the new destination virtual disk, Hyper-v fails back to run on the original source files.