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 2-12). 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.

• Token
• Offload
• Read Token Token
• Offload
• Write
• Virtual Actual Data Transfer
• Virtual
• Intelligent Storage Array

FIGURE 2-12 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:

■ Expansion of dynamic VHDs

■ Merging of VHDs

■ Live Storage Migration

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

Deprecated and removed networking and Hyper-V features

ertain networking and Hyper-V features have been deprecated in Windows

Server 2012, which means that these features likely will not be included in future versions of Windows Server. The features that are now deprecated include:

■ The Network Driver Interface Specification (NDIS) version 5.0, 5.1, and 5.2

application programming interfaces (APIs)

■ The WMI Root\Vvirtualization namespace (replaced by the new namespace

Root\Virtualization\v2)

■ Windows Authorization Manager (AzMan)

In addition, support for the following networking and Hyper-V features has been removed from Windows Server 2012:

■ SMS.sys (SMB functionality is now provided by the Winsock Kernel)

■ VM Chimney (also called TCP Offload)

■ Static VMQ

■ NetDMA

Support for 4 KB sector disks

Windows Server 2012 now includes support for large-sector disks. These disks represent
the newest trend in the storage industry whereby the old 512-byte sector format is being replaced by the new 4,096-byte (4 KB) format to meet demand for increased disk capacity. Hyper-V in Windows Server 2012 now supports hosting VHD files on disks that have either the native 4-KB format or the transitional 512-byte emulation (512e) mode.

4 K sector support and the real user

ith the introduction of Advanced Format storage devices, vendors found

the way to increase effectiveness of error correction schemas for large hard

drives. The change of format, however, brought certain difficulties.

All versions of Windows up to Windows 7 SP1 support native 512-byte sector read/writes, and via a special emulation method called 512e, can work with bigger sector drives, hiding the physical sector size over logically presented 512-byte values.

However, some file formats are hard-coded to work with physical sectors and won’t accept values other than 512 bytes. VHD specification version 1.0 is a sample of

such a format. You can connect a brand-new 4 TB disk to Windows 7 or Windows Server 2008 R2, and you can put your media or data on it. You’ll fail to create a VHD for Hyper-V or iSCSI. Even if you copy VHD to the drive, you would fail to use it. Windows 8 and Windows Server 2012 bring native support for the Advanced format, as well as the updated VHD and VHDX specifications.

Blogger Labels: Data,Transfer,Another,performance,improvement,Windows,Server,storage,mechanism,destination,servers,Figure,Token,Offload,Read,Write,Virtual,Actual,Intelligent,Array,Hyper,environment,environments,example,Expansion,VHDs,Live,Migration,database,versions,Network,Driver,Interface,Specification,NDIS,version,interfaces,APIs,Root,Virtualization,Virtualization,Authorization,Manager,AzMan,addition,Winsock,Kernel,Chimney,Static,NetDMA,Support,sector,disks,trend,industry,disk,emulation,mode,user,Format,vendors,error,correction,schemas,method,size,sectors,media,VHDX,specifications,namespace,byte