Q: What's the difference between the VDI server and file server mode for data deduplication in Windows Server 2012 R2?
A: Data deduplication was enhanced in Windows Server 2012 R2 to support the deduplication of Hyper-V virtual machines when used in Virtual Desktop Infrastructure (VDI) scenarios. To provide this support, data deduplication was enhanced to support the deduplication of exclusively locked files. To enabling deduplication, you must select the General purpose file server option, as shown in the following figure.
The easiest way to see the difference between the two modes is to configure each one in turn, then look at the full configuration. For example:
PS C:\> Enable-dedupvolume d: -UsageType HyperV
Enabled UsageType SavedSpace SavingsRate Volume
------- --------- ---------- ----------- ------
True HyperV 1.64 TB 78 % D:
PS C:\> Get-dedupvolume d: | fl
Volume : D:
VolumeId : \\?\Volume{31e426a7-de3e-11e1-93ed-90e2ba06f9d7}\
Enabled : True
UsageType : HyperV
DataAccessEnabled : True
Capacity : 1.82 TB
FreeSpace : 1.37 TB
UsedSpace : 462.47 GB
UnoptimizedSize : 2.09 TB
SavedSpace : 1.64 TB
SavingsRate : 78 %
MinimumFileAgeDays : 0
MinimumFileSize : 32768
NoCompress : False
ExcludeFolder : {\WindowsImageBackup}
ExcludeFileType :
ExcludeFileTypeDefault : {bin, vsv, slp, xml...}
NoCompressionFileType : {aac, aif, aiff, asf...}
ChunkRedundancyThreshold : 100
Verify : False
OptimizeInUseFiles : True
OptimizePartialFiles : True
PS C:\> Enable-dedupvolume d: -UsageType Default
Enabled UsageType SavedSpace SavingsRate Volume
------- --------- ---------- ----------- ------
True Default 1.64 TB 78 % D:
PS C:\> Get-dedupvolume d: | fl
Volume : D:
VolumeId : \\?\Volume{31e426a7-de3e-11e1-93ed-90e2ba06f9d7}\
Enabled : True
UsageType : Default
DataAccessEnabled : True
Capacity : 1.82 TB
FreeSpace : 1.37 TB
UsedSpace : 462.47 GB
UnoptimizedSize : 2.09 TB
SavedSpace : 1.64 TB
SavingsRate : 78 %
MinimumFileAgeDays : 0
MinimumFileSize : 32768
NoCompress : False
ExcludeFolder : {\WindowsImageBackup}
ExcludeFileType :
ExcludeFileTypeDefault : {edb, jrs}
NoCompressionFileType : {aac, aif, aiff, asf...}
ChunkRedundancyThreshold : 100
Verify : False
OptimizeInUseFiles : False
OptimizePartialFiles : False
As you can see, the major difference between the two modes is that using Hyper-V (the first configuration) enables the deduplication of in-use files (i.e., virtual machine virtual hard disks) and optimizes partial files. In addition, the configuration files' extensions for virtual machines are automatically excluded from deduplication. Therefore, if you want to deduplicate Hyper-V virtual machines you must choose the Hyper-V (VDI) configuration option.
