The reason why Microsoft gives you the option of waiting until a file is a few days old before it is be duplicated is because the deduplication process consumes system resources such as CPU cycles and disk I/O.
You really don't want to waste these resources on deduplicating temporary files.
Cluster shared volumes also cannot be deduplicated.
Although deduplication features have existed in storage hardware for years, the release of Windows Server 2012 marks the first time that Microsoft has allowed deduplication to occur at the operating system level.
When the Add Roles and Features Wizard launches, navigate through the wizard until you reach the Add Roles screen.
Expand the File and Storage Services role, and then expand the File and i SCSI Services container and select Data Deduplication, as shown in Figure 1. To do duplicate a volume, open the Server Manager and select the Volumes container.
The File Extensions to Exclude setting lets you avoid wasting system resources by preventing Windows from trying to do duplicate files that most likely will not benefit from the deduplication process.
Similarly, if you have folders containing compressed files you can exclude those folders from the deduplication process.