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Solaris ZFS Administration Guide

Replacing a ZFS File System With a ZFS Clone

You can use the zfs promote command to replace an active ZFS file system with a clone of that file system. This feature facilitates the ability to clone and replace file systems so that the original file system becomes the clone of the specified file system. In addition, this feature makes it possible to destroy the file system from which the clone was originally created. Without clone promotion, you cannot destroy an original file system of active clones. For more information about destroying clones, see Destroying a ZFS Clone.

In the following example, the tank/test/productA file system is cloned and then the clone file system, tank/test/productAbeta, becomes the original tank/test/productA file system.


# zfs create tank/test
# zfs create tank/test/productA
# zfs snapshot tank/test/productA@today
# zfs clone tank/test/productA@today tank/test/productAbeta
# zfs list -r tank/test
NAME                   USED  AVAIL  REFER  MOUNTPOINT
tank/test              314K  8.24G  25.5K  /tank/test
tank/test/productA     288K  8.24G   288K  /tank/test/productA
tank/test/productA@today      0      -   288K  -
tank/test/productAbeta      0  8.24G   288K  /tank/test/productAbeta
# zfs promote tank/test/productAbeta
# zfs list -r tank/test
NAME                   USED  AVAIL  REFER  MOUNTPOINT
tank/test              316K  8.24G  27.5K  /tank/test
tank/test/productA        0  8.24G   288K  /tank/test/productA
tank/test/productAbeta   288K  8.24G   288K  /tank/test/productAbeta
tank/test/productAbeta@today      0      -   288K  -

In the above zfs list output, you can see that the space accounting of the original productA file system has been replaced with the productAbeta file system.

Complete the clone replacement process by renaming the file systems. For example:


# zfs rename tank/test/productA tank/test/productAlegacy
# zfs rename tank/test/productAbeta tank/test/productA
# zfs list -r tank/test
NAME                   USED  AVAIL  REFER  MOUNTPOINT
tank/test              316K  8.24G  27.5K  /tank/test
tank/test/productA     288K  8.24G   288K  /tank/test/productA
tank/test/productA@today      0      -   288K  -
tank/test/productAlegacy      0  8.24G   288K  /tank/test/productAlegacy

Optionally, you can remove the legacy file system. For example:


# zfs destroy tank/test/productAlegacy