Hyper-V Server Offload data transfer (ODX)

When copying and moving files between SAN drives, offloaded data transfer (ODX) technology offloads the CPU and network load to the SAN hardware. This feature is ideal for cloud environments that require the provisioning of new virtual machines from the virtual Machine template Library, or where large volumes of data are replicated after virtual disk operations, such as virtual disk consolidation, storage migration, and live migration. Storage devices that perform such operations must be able to support offloading (such as ISCSI, Fibre Channel Sans, or Windows server R2 file servers that support offloading), which Hyper the host's processor to handle more virtual machine load.

Without ODX, customers may need to consume significant network bandwidth and use a significant amount of CPU and memory resources to perform certain data-related tasks, such as large file replication or virtual machine storage migrations. The operations of these tasks can also take a significant amount of time, even in high-speed 10GbE networks, which can cause significant performance degradation in the course of a task.

Offloaded data Transfer (ODX) in Windows Server R2 allows you to more fully leverage existing external storage arrays, quickly move large files and virtual machines between storage arrays, and reduce host CPU and network bandwidth usage. With the use of SAN storage hardware that supports offloading, ODX can perform file copy operations through the storage device without occupying the Hyper-V host CPU resources, and the storage device reads the data directly from one storage location and writes to another location.

ODX uses a token-based mechanism to read and write data inside or between smart storage arrays. It is no longer necessary to transfer all the data through the host, only a small token is copied between the source and destination location. This token actually represents the point-in-time state of the data. For example, copying a file or migrating a virtual machine at a storage location, either inside or between a storage array, is actually a token that represents a VM file, so it is no longer necessary to replicate the underlying data through the server. In a token-based copy operation, the action shown will occur:

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In a SAN that supports ODX, when a user copies a file from one volume to another, the following occurs automatically (even support for copy and paste operations through the resource manager):

1. Users use Windows Explorer, the command line interface, or the Virtual Machine Migration Wizard to copy or move files.

2. Windows Server 2012 automatically converts the request to ODX (provided storage array support) and obtains a token representing the data.

3. Copy the token between the source server and the destination server.

4. Submit the token to the storage array.

5. The storage array performs file copy or move operations internally and displays the operation status for the user.

Prerequisite Requirements

To use Hyper-V support for ODX, the following conditions are true:

1) Windows Server 2012, Windows Server R2, Hyper-V Server 2012, or Hyper-V server R2.

2) The virtual disk file is saved on the hardware that supports ODX and is connected to the virtual machine by means of a virtual SCSI device or straight-through disk.

3) Assign an ODX-compatible fibre Channel LUN to the virtual machine's virtual Fibre Channel adapter.

4) VHD or VHDX virtual disks that are connected to the virtual IDE interface do not support this optimization because ODX is not supported by the integrated development environment (IDE).

1. To use the new ODX technology, you first need to collect Replication Manager (operating system) information about the storage array, which includes:

1) What is the name and version of the Replication Manager?

2) Does the Replication Manager support ODX?

3) Does the Replication Manager support ODX operations between multiple storage arrays from the same vendor?

4) What is the default value for inactive timers? This specifies how long the replication Manager waits for the idle token to expire after the timer expires.

5) What is the maximum token capacity of the Replication Manager?

6) What is the optimal transfer size? This indicates how Windows sends "read" and "write" commands that are the most appropriate size for the storage array.

I don't know much about ODX, mainly through the TechNet website.

Http://technet.microsoft.com/zh-cn/library/hh831487.aspx

2. Use the command to verify that the server for ODX you want to use supports ODX technology

Query the registry key with administrator rights to determine if the filter driver has optionally joined ODX support

Get-itemproperty hklm:\system\currentcontrolset\services\<filtername>-name "SupportedFeatures"

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3. Use the following command to disable ODX on the server and create a system performance report during representative data transfer and establish a performance baseline

1) Open a Windows PowerShell session as an administrator

2) Check whether ODX is currently enabled (it is in the default state) by verifying that the Filtersupportedfeaturesmode value in the registry is equal to 0

Get-itemproperty hklm:\system\currentcontrolset\control\filesystem-name "Filtersupportedfeaturesmode"

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3) Disable ODX support by using the following command

Set-itemproperty hklm:\system\currentcontrolset\control\filesystem-name "Filtersupportedfeaturesmode"-value 1

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4) Open Server Manager, click the top Right tool, select Performance Monitor

5) Expand Data Collector Set and system, right-click System Performance Performance, and then click Start. Performance Monitor will take 60 seconds to collect data

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6) Expand Reports, expand Systems, expand System Porformance, click Generated performance reports, view CPU usage, network usage, Disk Bytes/sec-related data

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4. Enable ODX and verify performance

1) Open the Windows PowerShell session as an administrator and type the following command

Set-itemproperty hklm:\system\currentcontrolset\control\filesystem-name "Filtersupportedfeaturesmode"-value 0

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2) Perform the above steps again, expand Data Collector Set and system, right-click System Performance Performance, and then click Start.

3) When evaluating the performance of ODX, you should review the differences between the baselines created when you disable ODX

A) The CPU usage should be low (only slightly higher than before the data transfer). This indicates that the server does not need to manage data transfer.

b) Network usage should be low (only slightly higher than before data transfer). This shows that the data transfer bypasses the server.

c) The value of Disk Bytes/sec should be higher. This reflects the increased performance of direct transmission within an array or SAN.

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Enable (or re-enable) ODX to repeat baseline tests and compare results. If ODX is expected, the CPU and network utilization should be lower because the server's CPU and NIC ports do not handle the transfer work directly, and the disk activity should be higher because the data is being executed more efficiently on disk-disk (rather than disk-server-disk). If the results are reversed, you need to confirm that ODX is fully enabled and re-checking the configuration of Windows servers, storage arrays, storage protocols, and other requirements. Repeat the ODX baseline test periodically to find any signs of deterioration that may require troubleshooting, optimization, or upgrades.

By avoiding server interference to move data directly between storage locations, offloaded data transfer improves storage efficiency. However, ODX support is not yet widespread and users must consider hardware and software compatibility requirements. It is best to test for ODX configuration and performance benefits in a lab environment, especially for hybrid storage array hardware or versions of Windows Server and storage filter drivers. Planning and testing can avoid costly performance costs when the storage system is accidentally forced to return to non-ODX operations.

This article is from the "Xu Ting blog" blog, make sure to keep this source http://ericxuting.blog.51cto.com/8995534/1590827

Hyper-V Server Offload data transfer (ODX)