Changing from thick to thin in ONTAP 9?

[Northman]

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?

[Ontapforrum · Accepted solution]

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

[Northman]

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%

[Ontapforrum]

::> 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)

[Northman]

ok, thanks.