Synology Community
community.synology.com › enu › forumFeb 18, 2019 · Hello everyone. According to the past experience, most Synology iSCSI users may hit one problem after using iSCSI service for a long time. It's: The used space of my Thin-Provisioning LUN doesn't decline after deleting files on the LUN disk. The most root cause is that VM may need to issue UNMAP commands from the host to reclaim the space.