topic Re: Lun Reclaim from unix end and yet at storage end it does not show released size in Data Protection

Lun Reclaim from unix end and yet at storage end it does not show released size

backupstorage — Wed, 04 Jun 2025 10:09:10 GMT

Hi team,

We are in process of reclaiming space from linux server and ran the command of fstrim also but at the storage end it does not show same space reclaimed.

Anything from storage to check or scan to have relase space from storage end

Regards,

Re: Lun Reclaim from unix end and yet at storage end it does not show released size

pedro_rocha — Wed, 10 Nov 2021 14:04:41 GMT

Hi,

Is it a LUN or NFS mount?

fstrim did any reclamation or none at all?

fstrim -v gives the potential reclaimable data?

is the volume/lun THIN?

Regards,

Pedro.

Re: Lun Reclaim from unix end and yet at storage end it does not show released size

Ontapforrum — Wed, 10 Nov 2021 14:23:34 GMT

Two things:

1st - You didn't mention which *nix, KB here.

https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/What_are_the_recommendations_for_the_host_stacks_supporting_SCSI_UNMAP_(TRIM)_commands%3F

2nd - In any case, If the Host OS TRIM is manually done, then ensure this option is enabled.

-space-allocation enabled (This option enables ONTAP to reclaim space automatically when your host deletes data. It is set to disabled by default.)

Steps here: (You need to follow the exact steps)

https://docs.netapp.com/us-en/ontap/san-admin/enable-space-allocation-scsi-thin-provisioned-luns-task.html

Re: Lun Reclaim from unix end and yet at storage end it does not show released size

backupstorage — Thu, 11 Nov 2021 11:20:12 GMT

@pedro_rocha @Ontapforrum Thank you for reply

volume/lun THIN? Yes it is Thin provisioned

reclaim space automatically is enabled already

fstrim -->it didn't help much there is difference of 200 GB

Please help to know if anything has to be done on it.

Re: Lun Reclaim from unix end and yet at storage end it does not show released size

pedro_rocha — Thu, 11 Nov 2021 14:09:22 GMT

is it a LUN (iSCSI / FC) or volume (NFS)?

as @Ontapforrum said, if LUN, -space-allocation was enabled after it was presented to the host? If yes you should rescan

which file system are you using if LUN?

did you review this? https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/Storage_auto-reclamation_does_not_occur

Re: Lun Reclaim from unix end and yet at storage end it does not show released size

backupstorage — Thu, 11 Nov 2021 14:25:43 GMT

@pedro_rocha Will check and get back to you accordingly

Re: Lun Reclaim from unix end and yet at storage end it does not show released size

backupstorage — Tue, 16 Nov 2021 07:28:39 GMT

@pedro_rocha

which file system are you using if LUN? Lun is ISCI

yes we did review the above KB and space-allocation enabled is already set

Let me know if below rescanning is required to be done

PS Link Refer

https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/How_to_rescan_and_recover_LUN_paths_in_a_host_after_modifying_SLM_reporting_nodes

Linux hosts:

Rescan after add-reporting-nodes.
1. Starting RHEL 6.5 & RHEL 7.0 onwards, run the following command to update active/optimized paths after add-reporting-nodes:
  # /usr/bin/rescan-scsi-bus.sh –a
2. For RHEL 5 and RHEL 6.4 (including previous updates), run the following command to update active/optimized paths after add-reporting-nodes:
  # /usr/bin/rescan-scsi-bus.sh
  Note: Nothing additional has to be done in the multipath layer.
Rescan after remove-reporting-nodes
1. Separate rescan steps are required for SCSI layer and Multipathing layer in Linux storage stack to clean up stale disk paths after remove-reporting-nodes in SLM.
2. Run the following command to remove stale LUN paths in SCSI layer
  # /usr/bin/rescan-scsi-bus.sh –r
3. Next run the following command to remove stale LUN paths in multipath layer:
  # multipath -r
  Note: The /usr/bin/rescan-scsi-bus.sh script is available as part of the native sg3_utils package.

Anything from the storage end scan can be done ?

Scanning on storage end will it require reboot ?

If Scanning is possible on storage end , is it disruptive operation?

Thanks in advance

Re: Lun Reclaim from unix end and yet at storage end it does not show released size

pedro_rocha — Tue, 16 Nov 2021 18:54:53 GMT

Hi,

rescan is required if the LUN has been changed space-allocation from disabled to enabled

it should not pose any downtime to rescan

you can do any kind of rescan from the storage side

you should run fstrim to reclaim the space after all