topic Re: LUNs not visible in Windows backup server in ONTAP Discussions

LUNs not visible in Windows backup server

Jerry2 — Wed, 04 Jun 2025 09:46:47 GMT

Dear Netapp gurus!

We want to use SAN mode for backuping up VMs, that are on the VMFS datastores. These datastores are built upon the SAN LUNs created in Netapp Ontap. However, we are able to see only one LUN. Is it possible, that other volumes (LUNs) with larger size 16TB and above are not visible for Windows OS? In fact, they are displayed in disk management, but not recognized by windows os and backup software. Unfortunately we have restarted related services and the whole server without any results. Of course, we keep in mind, that these LUNs cannot be initialized or even online, because there could be file system corruption when both Windows and VMware can write to them.

Re: LUNs not visible in Windows backup server

paul_stejskal — Wed, 26 Jul 2023 13:45:00 GMT

You shouldn't be mounting VMware LUNs on Windows. The file system differences are probably throwing it off or Windows itself may know something is up. If you need to back your system up, I'd talk to the account team about using our suite of products. We even have the ONTAP tools for VMware to do basic backups I believe.

Re: LUNs not visible in Windows backup server

Jerry2 — Wed, 02 Aug 2023 11:48:33 GMT

Hi @paul_stejskal , thank you for your input. Unfortunately, we use backup software (Commvault) in order to backup data to disks and tapes. There is something that can not be changed. In fact, we have followed this well described procedure, but the datastores are still not visible for backup software - https://www.nakivo.com/blog/using-san-vm-backup-recommendations/

Re: LUNs not visible in Windows backup server

pedro_rocha — Wed, 02 Aug 2023 19:29:41 GMT

Hi, other VMware DS, smaller than 16TB are being shown (other than the one you are already seeing)?

I've done something similar with Linux Commvault MAs.

Re: LUNs not visible in Windows backup server

Jerry2 — Mon, 07 Aug 2023 08:43:49 GMT

Hi @pedro_rocha , it seems to be the case. Indeed, the Datastores smaller than 16TB are visible well. Unfrotunately, our datastores are quite bigger. Do you have any explanation for this issue?

Re: LUNs not visible in Windows backup server

pedro_rocha — Mon, 07 Aug 2023 13:12:05 GMT

Hi. Are you using ONTAP 9.12? Because before that, max lun size was 16TB.

If you are using 9.12, I recommend you to open a case with Commvault, as they probably have faced this situation.