You can create a storage policy copy with deduplication and assign it to a storage pool with global deduplication.
Before You Begin
Before assigning a storage policy copy to a global deduplication policy, consider these guidelines:
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Storage pool with global deduplication must be assigned at the time of storage policy or copy creation. When assigned, you can neither change nor disable storage pool. 
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Existing storage policy copies cannot be configured for global deduplication. 
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No two storage policy copies in a storage policy can be associated with the same storage pool. 
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When configuring global deduplication between copies, ensure that the MediaAgents of all copies have access to the DDB. 
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If multiple MediaAgents are used, then the disk library that contains the DDB must be configured as a static share library. 
Procedure
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From the CommCell Browser, expand Policies > Storage Policies. 
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Right-click the appropriate storage policy and then click All Tasks > Create New Copy. 
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In the Copy Properties dialog box, enter the appropriate information. - 
In the Copy Name box, type a name for the copy. 
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Select the Use Global Deduplication Policy check box, and then select the name of a storage pool with global deduplication from the list. 
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Click OK. 
 The storage policy copy appears under the appropriate storage policy. 
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