Windows Server 2012 : Increase scalability and performance (part 3) - Offloaded Data Transfer, Support for 4 KB sector disks

3. Offloaded Data Transfer (ODX)

Another performance and scalability improvement in Windows Server 2012 revolves around storage, in particular when storing VMs on storage arrays. Offloaded Data Transfer (ODX) is a feature of high-end storage arrays that uses a token-based mechanism to read and write data within and between such arrays. Using ODX, a small token is copied between the source and destination servers instead of routing data through the host (see Figure 4). So when you migrate a VM within or between storage arrays that support ODX, the only thing copied through the servers is the token representing the VM file, not the underlying data in the file.

Figure 4. How offloaded data transfer works in a Hyper-V environment.

The performance improvement when using ODX-capable storage arrays in cloud environments can be astounding. For example, instead of taking about three minutes to create a new 10 GB fixed VHD, the entire operation can be completed in less than a second! Other VM operations that can benefit just as much using ODX-capable storage hardware include:

ODX also can provide benefit in nonvirtualized environments, such as when transferring large database files or video files between servers.