Used capacity in NetApp storage is not sync with used capacity on OS level

[madi]

Hi all,
i am working on to expand the volume from NetApp storage and resize it on OS server.
What i have done so far was as below:

-Unmount the existing path and delete the old volume group.
-Expand the LUN from NetApp controller and mount it into a server.
-Create the LVM from new mounted volume.
-Resize the volume on OS level.

The problem that i am facing right now is the LUN in NetApp storage is still showing 49% used
capacity but it shows 1% used capacity on OS level.
I have deleted all the snapshots but it still didnt clear up my used capacity in NetApp storage.

The used capacity in NetApp storage should reduce to 1% following the same used capacity on OS level. (correct me if i'm wrong)

Below are my specs:
NetApp controller OS: Data ONTAP 8.2P2
Server OS:RedHat Enterprise Linux 6.2
Using iscsi protocol.

Kindly advice.

Thanks.

[AlexDawson · Accepted solution]

Hi there!

LUNs work like hard drives in that you interact with them at block level - you put a filesystem on them, and manage that filesystem with your attached client. When you delete a file from a client filesystem, it merely deletes the reference to those blocks. From the point of view of the SAN, those file blocks are still in use. We have a space reclaim option available for NTFS with snapdrive, but not for Linux - https://kb.netapp.com/app/answers/answer_view/a_id/1013508/~/space-not-reclaimed-after-migrating-data-off-lun-

It sounds like you've tried to reuse a LUN instead of creating a new one - the simple answer is that you should have created a new one in this scenario with these aims, but other than space used, there isn't a significant issue.

Hope this helps!