Current Issue: File Cluster Disk of 14 TB Size needs an CHKDSK which can't be done because it lasts too long. So I'm going to replace this disk in the storage of the cluster. I run many times the copyjob with robocopy. No problem at all till I saw a big difference.

My Issue: The new disk with the copied data needed 1 TB more diskspace than the original one. Is that caused by Dedup? I've deleted the volume and will restart the copyjob.

Env: Windows 2012 Server (no R2!)

Current Disk: Deduplication Active

New Disk: Copied files with robocopy

Robocopy command:

robocopy I:\ E:\ /E /COPYALL /PURGE /MIR /B /R:1 /W:1 /LOG:C:\Temp\robocopy\logfile.log /NFL /NDL /NP 

Should I exclude with /XP the System Information Volume? When I check the volume with treesize, it shows that 95% (on both drives) of the storage place is used from system volume information.

Deduplication is automatically active on the new drive. So what do I have to conisder for a safely way to copy my data?


Yes, you absolutely want to exclude "System Information Volume". Otherwise you risk wasting space on your source volume or corrupting already deduplicated files.

See https://support.microsoft.com/en-us/help/2834834/fsrm-and-data-deduplication-may-be-adversely-affected-when-you-use-rob

To complete your copy, you will probably have to set the dedup MinimumFileAgeDays setting to 0, and run robocopy more than once. When the copy fails due to lack of disk space, run dedup using the PowerShell command Start-DedupJob. Then run the copy again. You might have to repeat this process a couple of times until everything fits.

  • What's the reason to set the MinimumFileAgeDays to 0 on my current disk? Is it really nessesary? I'm currently saving 8 TB with MinimumFileAgeDays 5 days default. Are you talking about to set MinimumFileAgeDays to 0 on my new disk E:\? – donduc_jr Oct 16 '18 at 6:28
  • On your new disk. Because when you copy, all of the files will have an age of 0 days, so when you run the dedup job, none will be deduped. Now that I'm typing this out, it occurs to me that robocopy may maintain the last modified time, so this may not be necessary. But it's at least something to be aware of. – longneck Oct 16 '18 at 12:51
  • Alright thanks. The copy job is currently running and I will have a look after it has finished. – donduc_jr Oct 17 '18 at 10:26
  • My copyjob ended when there was no disk space left. So I deleted so directories to have 500 GB free space to enable data deduplication. I removed the disk from the fileserver where it later will run on and mounted it to my testserver (win2016) where I started the job Start-DedupJob -Type Optimization -Volume <Your-Volume-Here> -Memory 80 -Cores 80 -Priority High. My worries are, that I need more than 500 GB for Data Dedup, even though MS says 1 GB for every 1 TB of logical data when I check my old volume where I copy from. After Dedup finished, will my fileserver can handle this volume? – donduc_jr Oct 18 '18 at 8:32
  • My dedup job finished. It saved me almost 600 GB data of total diskspace in use with 13.6 TB (dedup savings included). This seems to be good. Looking forward to mount this drive on win2012 server later on – donduc_jr Oct 18 '18 at 14:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.