+3In data aging admin job, How can I see the quantity of space free released after this job completed.
I can see on SO level in media agent, I would expect to see some information about amount of space released clicking in detail of job but nothing is showed.
Is there way to get this type of granular information?
Best answer by Mike Struening RETIRED
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:
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!
+23That’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:
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!
+3wow, very detailed and good answer. I appreciate a lot.
Really, in my case is a disklibrary with deduplication. In a practical way I trying to administrate the amount of space with limited resources for this disklibrary.
So, is There some report that at least try to forecast in the next data aging jobs the amount of free space would be freed for next backup jobs?
+23Yup! There’s a report called the Data Retention Forecast and Compliance Report. You can run that against the library in question and there’s a chart on the bottom (this is the one I referred to above).
Let me know if you have any questions on the report!
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