List & sort ascending only total used space by all snapshots of individual datasets:

1

zfs list -r -o name,usedsnap -s usedsnap

List & sort ascending actual disk usage = disk usage from specific dataset without children dataset’s storage

1

zfs list -r -o name,usedds -s usedds

List all space related columns available in zfs list:

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zfs list -ro space

-s [column name] sorts zfs list output in ascending order by selected column’s data, -S [column name] sorts the same descending.