Yes, use everywhere virtio-scsi (via kvm with discard='unmap'). 'lsblk --discard' also shows discard is supported. vm's with xfs filesystem seem to behave better. -----Original Message----- Cc: lordcirth; ceph-users Subject: Re: [ceph-users] Re: guest fstrim not showing free space What driver did you use to mount the volumes? I believe only virtio-scsi supports fstrim commands.