How to enable periodic trimming in Openshift Data Foundations versions below 4.10?

Solution Verified - Updated 2022-04-21T08:46:08+00:00 -

Issue

In persistent RBD volumes provided by ODF, users might find discrepancies in between the used space in the file system mounted by an application pod, and the used value in the output of rbd du command in Ceph, for the matching image. This is normally the case after a massive file deletion. Sample outputs:

Application pod:
```
/dev/rbd0        20G   92M   20G   1% /var/lib/pgsql/data
```
Ceph:
```
sh-4.4$ rbd -p ocs-storagecluster-cephblockpool du csi-vol-b80abc67-8344-11ec-86ee-0a580a83004b
NAME                                         PROVISIONED USED    
csi-vol-b80abc67-8344-11ec-86ee-0a580a83004b      20 GiB 5.0 GiB 
```
This discrepancy is normally corrected after running an fstrim command on the file system. For further information about fstrim, please refer to RHEL documentation. However, manually running this command is time consuming.
Is there any way to automate this task?

Openshift Data Foundation 4.9 and below.

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