Thin provisioning uses reference counts to indicate that data is shared between a thin volume and snapshots of the thin volume. There is a known issue with the way reference counts are managed in the case when a discard is issued to a thin volume that has snapshots. Creating snapshots of a thin volume and then issuing discards to the thin volume can therefore result in data loss in the snapshot volumes. Users are strongly encouraged to disable discard support on the thin-pool for the time being. To do so using lvm2 while the pool is offline, use the lvchange --discard ignore <pool> command. Any discards that might be issued to thin volumes will be ignored.