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Managed disk space used for what?

  • 12 October 2022
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J
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Hi, I’m struggling to understand the managed disk space feature. As I understand it will keep data on disk longer than retention requirements if there’s enough space on the disk library.

But does that go for all storage policies? For our normal storage policies using deduplication then the managed disk space is not active in the retention tab. And it’s not possible to activate. So does that mean that all jobs in this storage policy is not affected by the managed disk space feature? Or will jobs still be affected? Meaning that we might have old backup images on disk that actually should have been pruned?

Ideally I would like to ditch this feature to be fully in control of what is on disk as I don’t like the idea of having some data on disk underneath the hood or so to say. But as I understand it’s not possible to disable the feature as that’s how the data aging process works. But as much as possible I would like to limit the amount of extra backup images lingering around.

Currently we start to age 75% and stop at 60%.

Thanks.

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Best answer by Mike Struening RETIRED 18 October 2022, 19:24

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Mike Struening RETIRED
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Managed Disk Space can be a great feature IF you have a ton of leeway between all the parameters and ‘out of space’.  

You can (and likely should) disable it.

All MDS does is override the retention IF you have enough free space.  If you hit the 75%, then jobs will start to age in the order they would have otherwise, until you have 60% free space (or more).

Since the to-be-pruned job list is sent to age based on expected free space released, deduplication simply won’t work because the freed space won’t match the job size.

Here’s what I suggest:

Turn off MDS and run the Data Retention Forecast and Compliance Report on this copy.  See what will age off.  If you like what you see, run Data Aging.

If you don’t, turn it back on (and do all this when Data Aging is not set to run, of course!

https://www.linkedin.com/in/michael-struening
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Thanks Mike, that made me understand it better.

However, when you say disable it then I’m still not entirely sure where we do this. I can see there’s an option for this in the storage polices for the  primary disk copy. The “enabled managed disk space for disk library” is not checked and also greyed out. So does that mean that for this specific storage policy MDS is not being used and backup images is aged according to retention being honored?

Or will the actual thresholds of 75% and 60% still intervene with the backup images?

I understand that for the database log backup storage polices then MDS surely not should be activated since they’re not using deduplication.

Thanks again.

Mike Struening RETIRED
Rank
Userlevel 7
Badge +23

Thanks Mike, that made me understand it better.

However, when you say disable it then I’m still not entirely sure where we do this. I can see there’s an option for this in the storage polices for the  primary disk copy. The “enabled managed disk space for disk library” is not checked and also greyed out. So does that mean that for this specific storage policy MDS is not being used and backup images is aged according to retention being honored?

Or will the actual thresholds of 75% and 60% still intervene with the backup images?

I understand that for the database log backup storage polices then MDS surely not should be activated since they’re not using deduplication.

Thanks again.

If the option is not checked, then it is not in play for that Copy.  the thresholds are there to edit *IF* you enabled MDS, but do nothing to affect aging.

https://www.linkedin.com/in/michael-struening

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