Cross-Volume Dedup savings on AFF | NetApp | Page 1

tiny osprey Feb 19, 2024, 6:53 PM

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I need to find the total cross-volume dedup savings of a SSD-aggregate (AFF A400, ONTAP 9.12) but it seems like I can't find an aggregated number.

Cluster::*> aggr show-efficiency -fields aggr-compaction-saved,volume-efficiency-saved,volume-dedupe-zero-pattern-saved,volume-compression-saved
aggregate  volume-efficiency-saved volume-dedupe-zero-pattern-saved volume-compression-saved aggr-compaction-saved
---------- ----------------------- -------------------------------- ------------------------ ---------------------
1_AggrSSD1 8.87TB                  10.96TB                          4.57TB                   13.71TB
2_AggrSSD1 11.03TB                 17.51TB                          6.14TB                   15.09TB

Not sure if I can simply use the volume-efficiency-saved field which is the "Space Saved by Volume Deduplication". Does this maybe also include intra-volume dedup savings?

Tried some other combinations like aggr efficiency show, aggr efficiency cross-volume-dedupe show, vol efficiency show or even vol show-space. But I simply can't find a definite number.
Cross-volume savings should be reported at the aggr-level in my ONTAP version.

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I've went through the 100pages-monster-of-a-technical-presentation "ONTAP Storage Efficiency" on the fieldportal, but also no luck 🤷‍♂️

tiny osprey Feb 21, 2024, 10:18 AM

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No one? 😦

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These seem to be the guys who should know such things (according to the eff-presentation), but not sure if they're in here...

Product Manager: Christopher Hurley
TME: Mahalakshmi G

native pasture Feb 21, 2024, 11:12 AM

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@tiny osprey try mailto:<firstname>.<lastname>@netapp.com, that works in many cases 😉

tiny osprey Feb 21, 2024, 1:32 PM

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yeah, I've found the mail-addresses in the guide

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But currently it looks ok, I carefully encrypt volumes on the SSD aggr, to make sure they don't run out of space

tiny osprey Feb 21, 2024, 1:55 PM

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Tricky thing is that you apparently lose the cross-volume dedup savings only after the vol move is done (I guess once the original vol gets deleted). So can't really plan how much empty space you lose.

ember pier Feb 21, 2024, 2:34 PM

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@maiden osprey He's on here.

maiden osprey Feb 21, 2024, 3:40 PM

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all cross volume dedupe is lost when using NVE

tiny osprey Feb 21, 2024, 3:46 PM

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I know 🙂

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I need to know how much cross-volumes dedup savings I have

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How much usable space will I lose if I encrypt all the volumes to NVE? (which is needed as a 1. step to get to NAE volumes)

maiden osprey Feb 21, 2024, 3:59 PM

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gotcha...

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what version of ONTAP are we using?

tiny osprey Feb 21, 2024, 6:04 PM

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9.12.1P7

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we're planning to update to 9.13.1P7

elder acorn Feb 21, 2024, 10:15 PM

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Cross volume dedupe is viewed at aggr level.

tiny osprey Feb 22, 2024, 8:40 AM

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ok, and what's the command to view that specifically?

restive folio Feb 22, 2024, 10:15 PM

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storage aggregate efficiency cross-volume-dedupe

rocky juniper Feb 23, 2024, 4:56 AM

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What are the benefits if we encrypt the data at the volume level

tiny osprey Feb 23, 2024, 8:55 AM

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restive folio storage aggregate efficiency cross-volume-dedupe

But this cmd does not tell you how much you saved by the cross-volumes dedup. It only tells you when the last scan was, if it's currently running, etc. 🤷‍♂️
https://docs.netapp.com/us-en/ontap-cli-9121/storage-aggregate-efficiency-cross-volume-dedupe-show.html

storage aggregate efficiency cross-volume-dedupe show

Display aggregate cross volume deduplication efficiency details

tiny osprey Feb 23, 2024, 8:57 AM

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rocky juniper What are the benefits if we encrypt the data at the volume level

I don't want to use NVE... I want to use NAE so I can still have cross-volumes dedup.
But to get there I first need to encrypt all the volumes with NVE, then change my aggr to use an aggr-key and then encrypt all the volumes again with NAE.

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The only other way would be to have an empty aggr lying around where I can directly enable the aggr-key (which is only possible if the aggr is empty or all volumes are NVE encrypted).
I don't have an empty aggr though and not enough space to move all the volumes to one aggr.

drifting mist Feb 23, 2024, 9:01 AM

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there's always the old ' df -A -S -h -aggregate ' you can try...

tiny osprey Feb 23, 2024, 5:42 PM

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I have a clue:

The "deduplicated" field in df -A shows compaction savings according to the man-page.
And the number correlates with the "aggr-compaction-saved" field from aggr show-efficiency.

Interestingly the man-page says the following:
[-aggr-compaction-saved {<integer>[KB|MB|GB|TB|PB]}] - Space Saved by Aggregate Data Reduction (privilege: advanced) Displays the total disk space that is saved by data compaction, cross volume sharing at the aggregate level.
So my guess is that the cross-volume dedup savings are simply included in the compaction savings number.

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But... the same field in aggr show says nothing about "cross volume sharing":

         This parameter indicates the amount of the space saved by Data Compaction in bytes.```

So I also could be totally wrong... I don't understand why there is no one definite number for these savings... 🤷‍♂️

drifting mist Feb 23, 2024, 9:39 PM

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I'm going to go out on a limb and say that encryption is going to ruin most all of the cross-volume deduplication savings. Just the cost of doing such business.

shell moat Feb 23, 2024, 10:02 PM

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If you use NetApp aggregate encryption and all volumes are nae, then you get encryption and you get cross volume efficiencies.

If the encryption is happening before it gets to ONTAP then absolutely you be lucky to see any space savings.

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I had a customer decrypt a sql database and they ended up getting way better space utilization by letting ONTAP encrypt

drifting mist Feb 23, 2024, 10:12 PM

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at this point I'm just happy I don't need to deal with it. nothing is leaving my datacenters, hehe

#Cross-Volume Dedup savings on AFF