topic Re: Thick provisioning in AFF

Thick provisioning

TimmyT — Wed, 04 Jun 2025 12:26:05 GMT

Hi All,

Running Ontap 9.4sp5 on a FAS 2552 and AFF-A200.

I thought I knew what I was talking about but I am pretty confused right now after talking to co-workers and doing some more reading.

What we would like to do is go away from thin provisioned volumes and have the LUNS see all the space available to it. Right now we configure a 1:1 relatioship between volumes to luns. So I want my 10 TB volume to match my 10 TB LUN. On the volumes, I would have THIN PROVISIONED turned off, correct? And on the LUNS, do I disable space reservation?

Thanks.

Re: Thick provisioning

mrahul — Thu, 27 Jun 2019 05:11:37 GMT

Hi TimmyT,

LUNs with thick-provisioned volumes - space reservation is enabled.

Refer - https://docs.netapp.com/ontap-9/index.jsp?topic=%2Fcom.netapp.doc.dot-cm-vsmg%2FGUID-226B1E60-4ACF-4A63-9AE5-09E8605D53A2.html

LUNs with thin-provisioned volumes - space reservation is disabled.

Refer - https://docs.netapp.com/ontap-9/index.jsp?topic=%2Fcom.netapp.doc.dot-cm-vsmg%2FGUID-261F894C-F3E5-4D0F-ADF6-E5E4A5F65970.html&cp=17_3_10_2

Also, be noted that ONTAP supports T10 SCSI thin-provisioned LUNs as well as NetApp thin-provisioned LUNs. T10 SCSI thin provisioning enables host applications to support SCSI features including LUN space reclamation and LUN space monitoring capabilities for blocks environments. T10 SCSI thin provisioning must be supported by your SCSI host software.

You use the ONTAP space-allocation setting to enable/disable support for the T10 thin provisioning on a LUN. You use the ONTAP space-allocation enable setting to enable T10 SCSI thin provisioning on a LUN.

The [-space-allocation {enabled|disabled}] command in the ONTAP Command Reference Manual has more information to enable/disable support for the T10 thin provisioning and to enable T10 SCSI thin provisioning on a LUN.

Re: Thick provisioning

TimmyT — Thu, 27 Jun 2019 17:22:03 GMT

Thank you! That helped.

One more question. On one volume, I doubled the size from 3.5 TB to 7 TB. When I go to the LUN to resize it to 6.65 TB (5% rule), I then get the following error message

Space in the container colume is unsuffecient to expand the LUN. Do you want to expand the volume to accommodate the LUN?

Why am I getting this message?

Re: Thick provisioning

mrahul — Fri, 28 Jun 2019 03:59:02 GMT

You can just confirm clicking the "Ok" button of the dialog. The operation should be successfully completed.

Re: Thick provisioning

TimmyT — Fri, 28 Jun 2019 16:53:54 GMT

Thanks and sorry for pestering but I am a little confused.

I did what you said but now the volume size is 9.36 TB, how can this be when the total aggregate size is only 7.75 TB? Shouldn't the volume and aggregate max size match up?

Re: Thick provisioning

mrahul — Mon, 01 Jul 2019 04:10:11 GMT

You must have used aggregate overcommitment. The flex volumes that have created must have the property "space guarantee" of 'none' or 'file' so that the aggregate size does not limit the volume size.

Check the below link https://library.netapp.com/ecmdocs/ECMP1222473/html/GUID-19C01EAD-CA75-4C5B-950E-09338C376E88.html

I hope this clears your confusion.

Re: Thick provisioning

TimmyT — Tue, 02 Jul 2019 22:18:01 GMT

Thanks!

I won't say this clears up all my confusion (over provisioning an aggregate, thin provisioning a volume and lun, oh my!) but I will stick the with what is already working and go from there.

Cheers.