From LedHed's Wiki
Windows 2012 introduced deduplication as a new filesystem feature.
Contents
PowerShell Commandlets
Force Deduplication Job
Start-DedupJob D: –Type Optimization -Memory 30
This starts a new Deduplication job and will consume up to 30% of the system memory.
Check Dedup Job Status
Get-DedupJob
Check Dedup Savings
Get-DedupStatus
Reference
http://technet.microsoft.com/en-us/library/hh848450.aspx
http://blogs.technet.com/b/klince/archive/2012/04/02/fun-with-deduplication-in-windows-8-server.aspx