Windows Server Deduplication

I am running Windows 2012 R2 with data deduplication enabled. Duplicacy is installed on the server and set to make backup of the local drives.

From the logs I can see I am getting symlink errors stating the path cannot be found of the files. In windows explorer I can see the files exist but with 0 file size on disk.

How can duplicacy be configured to work with windows server deduplication?


Duplicacy should be capable of handing deduplicated files without special configuration.

File size being 0 is a bit weird. Can you run fsutil reparsepoint query on that file?

Typical error in log file

2019-11-06 00:00:52.703 WARN LIST_LINK Failed to read the symlink Data/Administration/Hospitality/Guesthouse/guest house/Old guest house information/Information of Dormitory 2 & 3 - 7/Transport Instruction between Airport & Guesthouse.docx:
The system cannot find the path specified.

fsutil reparsepoint query output:

Reparse Tag Value : 0x80000013
Tag value: Microsoft

Reparse Data Length: 0x0000007c
Reparse Data:
0000: 01 02 etc…
0010: 00 00 etc…
0020: 9d 58 etc…
0030: dd 98 etc…
0040: 60 5b etc…
0060: e0 90 etc…
0070: 61 ab etc…

All the files marked “WARN LIST_LINK Failed to read the symlink” does exist and can be read, so I don’t understand what is happening.


Maybe a permission issue?

It does not appear to be a permission issue as the other files with the same permissions work.
However, from the logs all the “symlink errors stating the path cannot be found” are reparse points.

Any ideas why duplicacy does not like windows server deduplication?

I have duplicacy_web_installer_win64_1.1.0.exe installed as a service through admin console.

The service runs under the localsystem account by default which may not have the right permission. Try change the account that the service runs under or simply run the web GUI as a normal application to see if it is permission related.

Isn’t this a duplicate of this other thread?

No. I am backing up local drives on local host, not network shares.

Ok after some tinkering… I got it to work using admin account in the service and removing -vss options.

With -vss options I am getting “WARN LIST_LINK Failed to read the symlink _filename” Any idea how to fix

In my test the -vss option works without an issue on a data deduplication volume.

Did you get the same The system cannot find the path specified error with -vss?

When -vss is enabled, a file is accessed via a different path. For example, d:\repository\file1 will be accessed as d:\repository.duplicacy\shadow\repository\file1, where d:\repository.duplicacy\shadow is a symlink pointing to the newly created shadow copy of d:.

So maybe you don’t have permissions to this shadow symlink? While duplicacy is running, try to access this file in File Explorer.

Yeah, you’re in a different situation than what I was. I am on V1.0 of the web GUI, and have had no problems backing up files on local drives with data deduplication enabled. (This is with Duplicacy running as admin.)

I have not tried the latest version yet, so I am curious what will happen when I update.