This is another installment in my series on Windows 8 Storage & Hyper-V. Previous blogs in the series can be found here:
Another promising new storage functionality that can be found in Windows Server 8 is the new transparent fast copy feature called Offload Data Transfer or ODX. If you know VMware’s vStorage API for Array Integration (VAAI), you probably know where to place ODX because it is more or less in the same league.
What’s the Challenge?
If you have a large Hyper-V guest with multi-Terabyte VHDX files, it depends on the amount of memory, the activity of the VM and the available bandwidth how long it takes to Live Migrate that VM to another node in your Hyper-V cluster. However, it is an entirely different story if you also need to move these very large VHDX files from one disk to another, from one array to another, from one cluster to another or even from one cloud to another. It would take ages doing this the classic way. Every read and every write including its confirmation would have to go through the sending server and the receiving server. Even if there would only be one Hyper-V server involved (copying between two CSV’s on the same server) this is highly inefficient. After all the VHD(X) is already on the storage array. Why let the data travel all the way from CSV1 through server A to server B and then back to CSV2 again? Why would the data have to leave the storage array at all?