Technical Stuff – Deduplicated Data Backup with DPM

One of our backup technicians escalated an issue to me today after they noticed it in the Data Protection Manager console recently. Nothing out of the ordinary I thought – Replica is inconsistent. Usually happens when the server is switched off incorrectly or crashes.


Then I noticed that the server raising the issue we recently enabled data deduplication on using Windows Server 2012. From there all the pieces began to fall into place:

The replica of volume e:\ on fss-staff is inconsistent with the protected data source. All protection activities for data source will fail until the replica is synchronized with consistency check. DPM is attempting to back up or restore a deduped file, which requires deduplication to be enabled on dpm. ID 30241 details: internal error code: 0x80900AD0)

Sure enough, we don’t have deduplication enabled on our DPM server because it is only Server 2008 R2, and not 2012. The solution in this case was to disable deduplication and deoptimise the drive – simply disabling it isn’t enough. You can do this by running the following command in PowerShell:

Start-DedupJob -Volume E: -Type Unoptimization

For reference, the technet article on protecting deduped volumes is here: and the specific line is: “You must enable the Data Deduplication role on the DPM server to protect deduplicated volumes.

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