Hey @Baba Imani !  I have a few questions:

1. Would these Aux Copies go to the same library?  Is library 2 and 3 the same cloud library (but logically different) or different locations altogether?
2. What is your end goal for retention?

Note that a Global Deduplication setup needs to use the same library:

Creating a Global Deduplication Policy

The global deduplication policy enables deduplication across multiple storage policies that use a common set of disk libraries and deduplication database (DDB).

We generally advise against Extended Retention on Deduplication.  You’ll end up increasing the size of the DDB.  However, this is likely your only option.

We don’t allow multiple copies in the same Storage Policy to use the same Global DDB….it would be a single point of failure for both copies.

Take a look at the docs in the links above and let me know if they help or if you have more questions.

Thanks for your response. Well the libraries are different in the sense that each Library is Blob storage in its own storage account. So no the aux copies won’t be going to the same library per Ada each goes to its own storage account with Local Redundant Storage. Why I’m also against extended retention is because I want to syncro copy a deduplicated Primary Copy to another region and if I have Ex Retention I’ll end up copying across data for all copies. 
 

The end goal for retention is

Dailies - 15 days to Primary Copy On Library 1 (deduped by Global DDB) Archive tier

Weeklies - 35 days in Library 2 (deduplicated) Cool/Archive tier

Monthlies - 13 months on Library 3 (deduplicated) Archive tier

*What are the ramifications enabling  deduplication on the secondary copies using a different folder location on a dedicated disk that isn’t the existing Global DDB disk when I create the policy copy? 

Thanks @Mike Struening. Yeah we have two MAs in the active cloud region and 1 in the DR region. I will go with setting up separate DDBs for each copy and last question. I was thinking to perhaps not deduplicate the Yearly copy as it only happens once a year. As for Access tiers and deduplication what’s the best practice given my intended setup. Say for the monthly copy with 13months retention and deduplicated. Was thinking Cool/Archive.

I would agree with Cool/Archive.  I imagine neither of them will be accessed all that often so these should suffice. 

Regarding deduplication, if you are only keeping it for 13 months, then you’d only be deduping against the previous backup (ignoring common blocks across clients).  It will definitely cut down on space, though not at some large percentage.

@Baba Imani Are we okay to close this off as an ongoing discussion within “Creating a Selective Copy Using a Library (Enable Deduplication)?