topic Re: Enable space allocation command in ONTAP Discussions

Enable space allocation command

IlirS — Wed, 04 Jun 2025 12:51:38 GMT

Hello,

I tried to use unmap command for a vmfs datastore but I got the following error:

"Devices backing volume 556c77e1-b49cf970-f474-10604ba82a40 do not support UNMAP"

I read that space allocation should be enabled for the corresponding lun in order to use this command.

I just wanted to know what is the impact of "lun set space_alloc <lun_path> enable" command?

I mean, is it safe to run this command on a production lun when the lun is online and used by many users ?

BR,

Ilir

Re: Enable space allocation command

paul_stejskal — Fri, 08 Feb 2019 15:15:04 GMT

7-mode or CDOT?

Re: Enable space allocation command

IlirS — Fri, 08 Feb 2019 16:18:28 GMT

7-Mode

Re: Enable space allocation command

paul_stejskal — Fri, 08 Feb 2019 16:22:38 GMT

The answer you seek is here: https://library.netapp.com/ecmdocs/ECMP1368845/html/GUID-AAA98EEC-0636-4EA8-96D4-FAFD95C94A29.html

Requires LUN offline according to that.

Re: Enable space allocation command

IlirS — Fri, 08 Feb 2019 16:29:27 GMT

Actually I ran the command without taking the LUN offline and everything was ok.

Thank you for your support anyway.

BR,

Ilir

Re: Enable space allocation command

paul_stejskal — Fri, 08 Feb 2019 16:33:19 GMT

I had a feeling it might work. It depends on the host OS probably how it handles it. But I think the documentation takes the "better safe than sorry" approach, which I share.

Re: Enable space allocation command

IlirS — Fri, 15 Feb 2019 13:13:52 GMT

Hello Paul,

Even after enabling space allocation I'm still facing:

"Devices backing volume 556c77b8-458abb2e-73f2-10604ba82a40 do not support UNMAP"

The output of "esxcli storage core device vaai status get -d naa.60a9800038303246792b475348684159" command is showing the delete status as unsupported.

naa.60a9800038303246792b475348684159
VAAI Plugin Name: VMW_VAAIP_NETAPP
ATS Status: supported
Clone Status: supported
Zero Status: supported
Delete Status: unsupported

Do you have any idea ?

BR,

Ilir

Re: Enable space allocation command

paul_stejskal — Fri, 15 Feb 2019 15:22:28 GMT

Have you checked this KB? https://kb.netapp.com/app/answers/answer_view/a_id/1001100

It might depend on a few things. I'd make sure you're on 8.2.5P1 (or is P2 out?) and start there. If you can't get it after that let's get a support case open so we can review your system individually. There probably is something simple but I'd have to look at an ASUP to have a better idea.

Re: Enable space allocation command

IlirS — Wed, 20 Feb 2019 10:24:27 GMT

Hello Paul,

The strange thing is that I have done the UNMAP procedure successfully on other vmfs datastores that are residing on this same Netapp storage. So, I think that it is not operating system Data ONTAP related isn't it ?

Regarding opening the case it is not possible for the moment since the end-customer has not renewed the Netapp storage system support yet :((

BR,

Ilir

Re: Enable space allocation command

Fra — Fri, 18 Oct 2019 09:02:24 GMT

Hello there,

we have the exact same problem.

We run a CDOT Release 8.3.2P3 and we'd like to enable space reclamation on the 4 online production LUNs.

Vsphere 6.5 is already configured for Space Reclamation (PriorityLow: Deleted or unmapped blocks are reclaimed on the LUN at low priority), but as i understand, this is not working on the NetAPP side due to space-allocation disabled.

Does CDOT version support enabling space-allocation on online LUN?

Thank you

Re: Enable space allocation command

paul_stejskal — Fri, 18 Oct 2019 15:00:28 GMT

8.3.2 does yes. The KB I linked above links https://kb.netapp.com/app/answers/answer_view/a_id/1003171. According to that you can.

Re: Enable space allocation command

Fra — Mon, 21 Oct 2019 07:11:48 GMT

Hello Paul,
thanks for reply. Prior to made any modification on the system i just wanted to be sure about the results. I had read the KB, and i've also picked up the Clustered Data ONTAP® 8.3 SAN Administration Guide (update 8.3.2, that is exactly our version).
And now i'm a bit confused: on page 41, "Enabling space allocation for SCSI thinly provisioned LUNs", the documentation clearly says for step 1 to "Take the LUN offline".
I fear that enabling space-allocation on an online LUN, even for CDOT series, still seems to be uncharted territory.
Can you give us a feedback about that?
Thak you very much

Re: Enable space allocation command

paul_stejskal — Mon, 21 Oct 2019 15:11:03 GMT

So, to avoid issues it's best to offline/online. If possible I would recommend a maintenance window to quickly flip the LUN.

Re: Enable space allocation command

aborzenkov — Mon, 21 Oct 2019 17:32:57 GMT

Does not this option change information returned when host queries LUN properties? Which means for this option to have any effect host needs to rediscover LYN?