Capacity different between Aggr used and volumes used total

[christsai]

Hi,

We have a A300 running ONTAP 9.6, and I  noticed the Aggr used capacity is different with total volume used on this Aggr .

Has anyone know why is the Aggr used different with total volume used ?

[TMACMD]

Thin Provisioning.

The graphic on the left indicates actual used capacity on the AGGR.

The graphic on the right I believe shows the capacity of the volumes on the AGGR without efficiencies.

Think of the result as if the data in the Volumes are fully hydrated.

[christsai]

Hi @TMACMD 

All volumes is thin provisioning except 2 SVM root volumes, and all volumes has enable efficiency function.

[TMACMD]

Exactly!

Look at that Used Capacity Column.

That should match the right portion of the first graphic.

Then look at the "used %" and "logical %".

One row is 50.65% used and 88% logical. 

The thin provisioning and efficiencies are working and doing what they are supposed to!

[christsai]

Hi @TMACMD 

The "Used data - 16.53TB"  is after efficiency data capacity,  so the all volumes "Used data" total capacity should be same as "Aggr Used- 8.15TB" , But in here 2 value is different ?

[Ontapforrum]

Could be b'cos you have a AFF-A300 which is a ALL-Flash array, and since 9.2 bydefault 'Dedupe' allows block-level sharing across volumes within an aggregate (i.e Aggregate level dedupe) which further reduces the physical used space needed to store data. So, logically 'used data' across your volumes is 16TB ; but actual space consumption on aggregate level is reduced.

This TR covers aggr/volume level efficiency concepts, worth having a look. 
https://www.netapp.com/us/media/tr-4476.pdf

Thanks!

[paul_stejskal]

Keep in mind, you have two different file systems here, WAFL at the aggregate level, and WAFL at the FlexVol level. Both of them now on AFF have the ability to do some form of storage efficiencies. Also, FlexVols can be thin or thick provisioned in the aggregate. So you have to think about what the counter is implying when you are looking at the data.