Specifications

Best Practices for Virtualizing and Managing Exchange 2013

To eliminate the inefficient and unnecessary steps required by traditional host-based file transfers, ODX

uses a token-based mechanism for reading and writing data within or between intelligent virtual storage

database volumes (Figure 16). Instead of routing the data through the host, a small token is copied

between the source and destination. The token serves as a point-in-time representation of the data. For

example, when you copy a file or migrate a virtual machine between storage locations, Windows Server

2012 copies the token representing the virtual machine file. This removes the need to copy the underlying

data between servers.

Figure 16: Offloaded Data Transfer in Windows Server 2012

The ESG Lab tested the efficiency and functionality of Offloaded Data Transfer. Two servers were

connected to an ODX-compliant Dell EqualLogic storage array.

The storage array consisted of 12 SAS

drives (600 GB each). A single RAID5 pool was created with two volumes: One contained a 75 GB virtual

machine, and the other was empty. Using an intuitive wizard, the ESG Lab configured a virtual machine

live migration from one server to another within a SAN. The lab specified the type of move, the server

receiving the data, move options, and destination virtual machine options. It then transferred a virtual

machine using the traditional non-ODX method and the new ODX method. The lab monitored network

utilization and elapsed time for the transfer to complete in both test cases.

The results in Figure 17 show noticeable improvements using ODX. The ODX transfer took approximately

6.5 minutes for the virtual machine to completely migrate to the other server, and the average network

bandwidth consumption was around 64 Kb/sec. Conversely, with non-ODX method, moving the 75 GB

virtual machine over the network took approximately 52 minutes and consumed 4 Mb/sec of network

bandwidth. The ODX method completed eight times faster than the non-ODX method, while consuming

virtually no server CPU or network resources.