used and backup column in machines overview
// From: Jonas Schwartze
two additional columns showing the used/avail properties of the machine (from zfs list) and the timestamp and/or state of the last backup would be helpful.
Backup can be just the state and timestamp columns of the last row of the backup overview of the respective machine.
Size can be calculated by e.g.
zfs list -H -r -o used /zones/$uuid.