Deduplication on Data Protection Manager is one of the most important feature that IT Pro wants, not only because the competitor give it since years but also because the amount of data grow-up faster. The great news of yesterday is that now is possible Dedup DPM Volume!
Keep in mind that this is not a core-feature but is a part of Windows Server 2012 R2 Volume Deduplication. The idea is put one, or more, .vhdx files into a Volume under Dedup; these files must be shared via SMB 3.0. vhdxs are configured as DPM Volume Storage to reduce the backup space. This scenario is enabled with the combination of DPM 2012 R2 UR4 and Windows Server 2012 R2 host and file servers with latest KBs on them.
The schema is similar like figure 1. Is not required a SOFS but if you want be “secure” is better have it.
Figure 1 – Dedup Schema
So take a look to White Paper on Deduplication of DPM Storage.