data aging admin job, How can I see the quantity of space free released after this job completed

That’s a very good question, and the explanation is a bit long…..so bear with me 

Assuming Deduplication is involved (which these days, is almost always the case), the Commserve itself is not really handling the actual pruning.

Here’s what happens at a high-ish level:

1. Data Aging runs on the CS and all logical Job IDs that have met all retention rules are marked for aging
2. The CS sends the Media Agent(s) a list of ALL of the individual Archive Files (MMDeletedAF table) from those aged jobs
3. The Media Agent(s) gets this list, and connects to the Dedupe Database (which has 3 tables: Primary - The unique block by hash, Secondary - the number of job references per Primary record, and ZeroRef - The primary blocks no longer referenced/needed)
4. The Media Agent applies the list of those Archive Files to the Secondary Table on the DDB and decrements 1 reference to each unique block in the list (from the CS)
5. Once complete, any Primary Record that has 0 references in the Secondary table is moved to the ZeroRef table
6. The Media Agent(s) involved in pruning will physically remove/delete the files in the ZeroRef table and update the DDB accordingly

Now that list is very high level and there’s all sorts of transactions and TIME involved, though I think you’ll start to see why the CS Data Aging job doesn’t show space reclaimed.  The truth is, it doesn’t know.  

The time between the logical DA job finishing and the totality of ZeroRef jobs being pruned can be hours….it can be a day in some cases.  The DDB decrementing phase (step 4) is the first time and place you can even get an idea of what will prune, it happens at step 5, and confirmed at step 6; however, there are so many caveats to the whole process that trying to claim an actual amount freed at any point becomes tough.

In some reports, we will display an amount to be pruned, though that is based off the App Size of those jobs compared to the average Dedupe Ratio.  It’s not accurate for a handful of jobs, but the bigger the sample size, the more correct it becomes.

Let me know if you want me to clarify anything in this process and I’ll be happy to do so!