Changing from thick to thin in ONTAP 9?

Northman — Wed, 04 Jun 2025 09:47:36 GMT

Is it correct that if a volume is wrongly set as tick and then changed to thin, the space is used and will not be freed if we change it to thin-type? The only way to fix this is to create a new volume and copy over the contents or do a vol copy with the right options?

Re: Changing from thick to thin in ONTAP 9?

Ontapforrum — Tue, 20 Jun 2023 09:03:37 GMT

I am not sure if I understood your query correctly. Anyway, you can correct me.

Used space will remain as is, just that the reserved allocated space (i.e Available space) which was reserved to the volume at the time of creation, will be FREED and given back to the containing Aggr.

It is a standard practice to set the volumes/LUN THIN, and either set autogrow or enable alerting, so that you are alerted when it reaches the threshold and you can manually expand it or let autogrow handle it. This can be performed on the fly (From THICK to THIN).

https://kb.netapp.com/onprem/ontap/os/How_to_convert_a_volume_or_LUN_from_thick_to_thin_provisioned

Re: Changing from thick to thin in ONTAP 9?

Northman — Tue, 20 Jun 2023 09:35:09 GMT

ok, but how long time to free up this space? As you can see, "Total Physical Used" stayed the same after making the volumes thin. "The used space" goes down. Bear in mind that the "Total Physical Used" is NOT the size of this aggregate. Is there a command to check the freeing of space you described?

aggr show-space -aggregate-name Aggr4

Aggregate : Aggr4

Feature Used Used%

-------------------------------- ---------- ------

Volume Footprints 2.12TB 1%

Aggregate Metadata 158.4MB 0%

Snapshot Reserve 0B 0%

Total Used 2.12TB 1%

Total Physical Used 1.97TB 1%

Total Provisioned Space 2.55TB 1%

aggr show-space -aggregate-name Aggr4

Aggregate : Aggr4

Feature Used Used%

-------------------------------- ---------- ------

Volume Footprints 1.96TB 1%

Aggregate Metadata 159.2MB 0%

Snapshot Reserve 0B 0%

Total Used 1.96TB 1%

Total Physical Used 1.97TB 1%

Total Provisioned Space 2.55TB 1%

aggr show-space -aggregate-name Aggr4

Aggregate : Aggr4

Feature Used Used%

-------------------------------- ---------- ------

Volume Footprints 1.43TB 1%

Aggregate Metadata 158.4MB 0%

Snapshot Reserve 0B 0%

Total Used 1.43TB 1%

Total Physical Used 1.97TB 1%

Total Provisioned Space 2.55TB 1%

aggr show-space -aggregate-name Aggr4

Aggregate : Aggr4

Feature Used Used%

-------------------------------- ---------- ------

Volume Footprints 1.43TB 1%

Aggregate Metadata 158.1MB 0%

Snapshot Reserve 0B 0%

Total Used 1.43TB 1%

Total Physical Used 1.97TB 1%

Total Provisioned Space 2.55TB 1%

Re: Changing from thick to thin in ONTAP 9?

Ontapforrum — Tue, 20 Jun 2023 09:52:25 GMT

::> df -A

Check the available column increasing, and capacity column decreasing.

Or,

::> aggr show

Check the Used% (It will go down) and Available column (it will increase)

Re: Changing from thick to thin in ONTAP 9?

Northman — Tue, 20 Jun 2023 09:57:35 GMT

ok, thanks.

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Changing from thick to thin in ONTAP 9?

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Re: Changing from thick to thin in ONTAP 9?