You can destroy a file system or dataset even if the dataset has dependent clones. A dataset's clone is automatically autopromoted when the origin dataset is destroyed. Snapshots of the destroyed dataset also automatically become hidden and no longer appear in the dataset listings. Being hidden, these snapshots cannot be cloned, held, or sent. Further, you cannot roll back to these snapshots.
With the autopromotion of clones, you no longer need to manually promote a clone to replace a destroyed dataset. Beginning with this OS version, the zfs promote command is deprecated.
The clone autopromote feature has caused some changes in the manner by which datasets are destroyed. Consequently, when you destroy a dataset, you might see unexpected results, such as the following:
The space occupied by snapshots of a dataset being destroyed becomes attributed to one of the clones that was promoted. You might therefore see that a dataset not even in use can suddenly grow in its use of disk space.
To ensure that a clone successfully replaces a destroyed dataset, clone auto-promotion will complete even if the replacement dataset exceeds the original quota. However, subsequent write operations to that dataset would fail because the quota has been surpassed.
By default, the destroy operation is performed asynchronously. The destroyed datasets are immediately reclaimed after the operation is completed and the destroy command returns to the caller. To perform a synchronous destroy operation, use the –s option when issuing the command.