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Notes from the Field: Converting Hyper-V Server to Windows Server

By Garth Jones

In a previous blog post I talked about Broadcom NIC issues that cropped-up when I upgraded a Hyper-V Server to Windows Server 2012 R2 Standard. In this blog post I’ll talk about the lessons I learned during the upgrade.

During the upgrade process I also needed to convert a pass-through disk to a VHDX file, adjust the RAID configuration, and convert the host to Windows Server 2012 R2 Standard. I decided to change the RAID configuration to RAID 1 for the host OS C:\ and RAID 5 to hold all the VHDX files on D:\. This was done to allow the maximum disk space without sacrificing performance on the VMs.

At a high level the following steps were performed.

1. Backed-up both VMs to a Network Attached Storage (NAS) device.

2. Created an iSCSI (Internet Small Computer System Interface) target that was bigger than the pass-through disk.

3. Installed Windows Server 2012 R2 Standard on the C:\ drive.

4. Attached the iSCSI target as T:\.

5. Used Hyper-V Manager to create a VHDX file; saved the file to T:\ using the pass-through disk as the source disk.

6. Validated that the VHDX file was created correctly.

7. Reconfigured 10 of the drives to a RAID 5 configuration.

8. Formatted and assigned the newly created drive as D:\.

9. Copied the original VHDX file to the new drive from the NAS device.

10. Copied the new VHDX file (pass-through disk) from the iSCSI target.

11. Created both VMs within Hyper-V Manager.

12. Removed the iSCSI target from the host server.

13. Tested the VMs to ensure they were working correctly.

14. Created new back-ups of both VMs to the NAS device, including the new VHDX file from the pass-through disk.

15. Kept the migrated VHDX file for approximately 14 days as a backup.

This plan may sound simple, but what did I learn?

· You can’t directly upgrade from Hyper-V 2012 Server to Windows Server 2012 R2 Standard. You must format the OS drive and start fresh.

· Even if you select a dynamically expanding VHDX file of 128 GB (default size) when you copy the pass-through disk to the VHDX file, it will take the original size of the pass-through disk.

· Converting from a pass-through disk to VHDX file is extremely slow! A 6TB drive took ~16 hours to convert.

· If you have a Broadcom NIC, regardless of which manufacturer (Dell, HP, etc.), you have to check your settings on the host server.

· Set aside at least a few days to complete this task!

If you have any questions, please feel free to contact me @GarthMJ.

Notes from the Field-Converting Hyper-V Server to Windows Server