LinuxQuestions.org - VMware storage reclamation in RHEL guests

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- - VMware storage reclamation in RHEL guests (https://www.linuxquestions.org/questions/linux-server-73/vmware-storage-reclamation-in-rhel-guests-4175477304/)

VMware storage reclamation in RHEL guests

We have several thin provisioned RHEL guests and supposedly storage reclamation is possible, if the file system is mounted with the discard option.
I have followed this reference.
So I went on and tested this with:
First I edited /etc/lvm/lvm.conf and changed issue_discards = from 0 to 1

Code:

mount -o remount,discard,rw /opt

dd if=/dev/zero of=/opt/bigfile.dat  bs=1M  count=6000

rm =/opt/bigfile.dat

fstrim -v /opt

Output: fstrim: /opt: FITRIM ioctl failed: Operation not supported
And from the VMware perspective the vmdk uses 6GB more space but does not decrease again.
Does anybody have any ideas about this?

Thanks for the link unSpawn, quite interesting for crypted ssd partitions which I may imply as soon as I have a ssd.
Our thin provisioned RHEL guests on the VM-farm do not have crypted partitions, so this does not apply.