Server 2012

Disable Dedup

Posted by robd on September 23, 2018
powershell, Server 2012 / No Comments

How to disable Dedup:

First an important point about disabling dedup (via GUI or PowerShell), when you disable it only stops further deduplication from occurring i.e data that has already been deduplicated will remain deduplicated

If you want to “move” the data back to the original files and out of the deduplication store (Chunk Store) you need to use powershell command

start-dedupjob -Volume <VolumeLetter> -Type Unoptimization

You can check the status on where this is at by using


Here’s another gotcha, chunk size (love that name) will not get smaller until you run two more commands, GarbageCollection and Scrubbing.  GargabeCollection will find and remove unreferenced chunks and scrubbing will perform an integrity check but this wont work unless dedup is on….so enable dedup:

Enable-DedupVolume -Volume <VolumeLetter>

Then run garage collection:

start-dedupjob -Volume <VolumeLetter> -Type GarbageCollection

start-dedupjob -Volume <VolumeLetter> –Type Scrubbin

Once your drive is small again then disable dedup:

Disable-DedupVolume -Volume <VolumeLetter>

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Microsoft Dedup

Posted by robd on September 22, 2018
Server 2012 / No Comments

I posted about Microsoft Dedup recently and thought I should mention how to setup dedupe:

Data deduplication is a feature that allows space reduction on a data volume by removing duplicate copy of data and replacing it with a reference file that looks exactly the same to the end user.

Microsoft does not recommend dedup on databases such as .edb, .mdf and .ldf files. This feature help IT admins reduce storage costs if it’s applied to the right data such as File shares such as home folders.

Below is the recommendation of dedup feature based on data type

Recommend Deduplication File Servers, VHD Files, Software Repositories, Backups and other static data.
Not Recommended Virtualization Hosts, WSUS, Database servers or any data that changes very frequently.


  • Windows Server 2012 Operating system
  • At least 4GB of RAM
  • 1 CPU core and 350MB of RAM for every 1.5TB worth of data
  • Must be on non-system volume such as boot volume
  • Mapped drives via net use is not supported. Must be a local volume.
  • Must be using NTFS with MBR or GPT partition
  • Not supported on ReFS file system

To install the deduplication feature, use the Server Manager – Server Manager > Server Roles > File and storage services > File services > Data Deduplication.

Or PowerShell

Run below powershell commands to install the feature
Import-Module ServerManager

Add-WindowsFeature -name FS-Data-Deduplication
Import-Module Deduplication
To turn on deduplication feature, use below command (where E is the volume)
Enable-DedupVolume E:
To Set the minimum file age before deduplication
Set-Dedupvolume E: -MinimumFileAgeDays 30
To get a list of deduped volumes, run
To get dedup status, run
To start a dedup job manually, run
Start-DedupJob E: -Type Optimization
To get current dedup schedule, run

How to calculate dedup rate

Installing the “Data Deduplication” feature will automatically install the DDPEVAL.exe in c:\windows\system32 . This tool will allow you determine if deduplication is effective your data type.

This tool can be copied from any server running Windows Server 2012 R2 or Windows Server 2012 to systems running Windows Server 2012, Windows Server 2008 R2, or Windows 7. You can use it to determine the expected savings that you would get if deduplication is enabled on a particular volume.

To use:

DPEval <VolumePath:>

C:\> DDPEVAL.EXE \\Server\Testshare

More info:


Dedup and Chunk Store is Huge!

Posted by robd on September 21, 2018
powershell, Server 2012 / 4 Comments

Found a drive was running low on space today and on closer inspection with tree size I found that ChunkStore (brilliant name) was taking up the drive space:

Odd as it looks as dedup wasn’t working:

To fix it I ran the following PowerShell:

start-dedupjob -Volume <VolumeLetter> -Type GarbageCollection

start-dedupjob -Volume <VolumeLetter> -Type DataScrubbing

What does this do I hear you say, Garbage collection is the process to remove “data chunks” that are no longer referenced i.e. to remove references to deleted files and folders. This process deleted content to free up additional space. Data scrubbing checks integrity and validate the checksum data.

To monitor it I ran:


This seems to have fixed it for me:

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DFS Referral Error

Posted by robd on June 30, 2017
DFS, Server 2012 / No Comments

Kept getting the below error today while access a share, annoying the redirection share of a desktop.

SHARE is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions

Element not found


Weirdly I could

Access the share from another server,

I could access the share using the direct share.

So I installed DFSUTIL.EXE on the server having the problem by installing “Distributed File system tools” windows feature.

Then ran:

dfsutil cache referral flush




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RDP Fails to Connect

Posted by robd on April 21, 2016
Server 2012 / No Comments

So today I couldn’t RDP to a Windows 2012 R2 server.

After arsing around for ages I stopped the Print Spooler Service and Boom, logged on!!!

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Server 2012 UAC – You don’t currently have permission to access this folder.

Posted by robd on May 13, 2014
Server 2012 / 1 Comment

Hi All,

Today I thought I’d setup roaming profiles on a Server 2012 file server, easy I thought, take me 10 minutes I thought…I was wrong.

So first things first, I created a share on my server with permissions:


Tested the share from another PC, great I can get on.

Jumped back on the server and tried to open the folder from the rout i.e. E:\Share\staff and I got the following

You don’t currently have permission to access this folder. Click Continue to permanently get access to this folder


Well if I click Continue then my share is ruined with ugly permissions I don’t want! I.e. I only want the permissions I specified above not my username dotted everywhere.

So I turned to UAC and disabled it:


No change, well thats mental……after a good hour of searching I found the answer was to set the registry to:


to 0


Reboot the server and all was fine in the world!!.

So why does UAC do this? UAC strips the admin credential from any un-elevated process. If you’re attempting to use an un-elevated process such as explorer to access a remote share using only admin credentials, UAC will strip the admin credentials from the process’ security token and the process will receive an “access denied” error.  Which is stupid if you changing permissions.

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