Thank you. Reading other posts I had believed it could be an either/or situation.
Is there any further steps beyond checking the 'discard' box for the disk in the webgui, any commands or a reboot needed afterward?
Any possible risks, e.g. for data loss? I am kind of surprised having discard...
I have a postfix/dovecot VM that was around 350GB and producing a 215GB gzip backup. I went and deleted about 200GB of email from this VM and now the 150GB VM is still producing a 215GB backup. The VM is on LVM-thin with the hypervisor on LVM running on SSDs. I do not have discard selected...