ZFS destroy error “cannot determine dependent datasets: recursive dependency”

Problem

In the following case, the origin of clone (datapool/ds1) is a snapshot of its descendant (datapool/ds1/ds2).

# zfs get -r origin datapool
NAME                PROPERTY  VALUE               SOURCE
datapool/ds1           origin    datapool/ds1/ds2@snap  -
datapool/ds1/ds2       origin    -                   -
datapool/ds1/ds2@snap  origin    -                   -

To destroy datapool/ds1/ds2, its snapshot datapool/ds1/ds2@snap needs to be destroyed.
To destroy datapool/ds1/ds2@snap, its dependent clone datapool/ds1 needs to be destroyed.
To destory datapool/ds1, its child filesystem datapool/ds1/ds2 needs to be destroyed.

Therefore, due to the recursive dependency, none of dataset/clone/snapshot under datapool/ds1 can be destroyed.

# zfs destroy -R datapool/ds1
cannot determine dependent datasets: recursive dependency at 'datapool/ds1'

Solution

This recursive dependency occurs when a clone which is a child of the origin’s parent was promoted like this.

# zfs create mpool/ds1
# zfs snap mpool/ds1@snap
# zfs clone mpool/ds1@snap mpool/ds1/ds2
# zfs promote mpool/ds1/ds2

Either of the following will resolve the recursive dependency.

1. Promote the clone

# zfs promote mpool/ds1

# zfs get -r origin mpool
NAME            PROPERTY  VALUE           SOURCE
mpool/ds1       origin    -               -
mpool/ds1@snap  origin    -               -
mpool/ds1/ds2   origin    mpool/ds1@snap  -

2. Rename the child dataset to a name which is not a child of the clone

# zfs rename mpool/ds1/ds2 mpool/tmp

# zfs get -r origin mpool
NAME            PROPERTY  VALUE           SOURCE
mpool/ds1       origin    mpool/tmp@snap  -
mpool/tmp       origin    -               -
mpool/tmp@snap  origin    -               -

Sunday, 21 October 2018