Copy offload

Offloaded data transfer (ODX) is a feature in Microsoft Windows Server 2012. ODX function frees up hosts and speeds the copy process by offloading the entire orchestration to a storage array.

For virtual machine (VM) operations and large data transfers, Microsoft ODX offloads the heavy lifting of data movement to the host storage array instead of doing normal read and write operations. Examples include copy operations such as:

VM creation
VM migration
VM cloning
Microsoft Windows Virtual Hard Disk (VHD) creation
VHD conversion
VM backup and recovery
File copy

ODX is most relevant in a Hyper-V environment for VM heavy lifting operations. Standard buffered copy is run by reading the data from the storage controller into the host, buffering it, and then writing it to another volume. The ODX function frees up hosts and speeds the copy process by offloading the entire orchestration to a storage array. This offloading is done by using tokenization for read operations and write operations, and it avoids buffering, which can ultimately cut down on processor cycles.

To enable the copy offload function, you must have subsystem device driver device-specific module (SDDDSM) version 2450 or later installed. ODX is disabled by default so that you can install the correct version of SDDDSM. After the correct SDDDSM version is installed, you enable ODX by entering the chsystem -odx on CLI command.