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Deduplication with Hyper-V in Windows Server 2012 R2


Yesterday in a client used my server to the System Center Demos and he became interested when he said that he used the resource Deduplication (or Dedup) of Windows Server 2012 R2. Consequently, the meeting migrated from System Center for optimization of disks with Hyper-V.

After all, the gain with Dedup in VHDs is impressive, coming in my case for almost 80% of additional space:


Important:First point in that conversation is make clear that Microsoft doesn’t support Dedup for Hyper-V in Hyper-V hosts for VMs into production. The reason is explained in TechNet, and basically it’s because Dedup in environment where the files are open can generate several errors:

“Deduplication of open files has not been fully validated for general virtualization or other applications, and additional issues may be encountered.”

However, there are always two questions in this case:

Question 1: But the Windows R2 2012 Dedup for PowerShell has the “Files” and “Hyper-V”, as it is not supported?

Reply:For Hyper-V is only supported for VDI environment, where the machines are SO client user. How VDI environments generally utilize the pool mode and a single VM is doubled with each new section, if 100 user are online we’d have 100 VHDs being dynamically created with duplicate data.
In this case it is clear that the use of Dedup will be supported, since the VHDs are dynamic and are constantly in use. Besides in general are used differencing disks, keeping the parent disk unchanged.

Question 2: If is not supported, because I am using? ;-)

Reply: Is not supported, but in my case it’s not the production environment and using Dedup manual:


I don’t keep my server all day connected, so when all the VMs are stopped, usually do it weekly, beginning the Job of Dedup with the command:

Start-DedupJob-Type Optimization-Volume X:

Then just monitor if the Job finished with Get-DedupJob:


So, my VHD files don’t run the risk of being manipulated while in use and I assure that periodically being updated the Dedup.

However, it is always good to remember that not to have problems the ideal is to have a disk or volume separately for the VHDs because Dedup configuration this volume will be configured as VDI (or Hyper-V in PowerShell):


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