ZFS and Jail :: nullfs mount :: nothing visible from host :: solved [partial]

[Miroslav Lachman]

Alexander Leidinger wrote on 2016/12/17 19:59:
> Quoting SK <fbstable at cps-intl.org> (from Fri, 16 Dec 2016 14:02:20 +0000):

>> If I understand you correctly, what you are suggesting is, the dataset
>> used by the jail itself for its root/base cannot be "worked on" from
>> within the jail, but if I define a different dataset (under the same
>> branch below the jail dataset), and attribute it to the jail, then I
>> can manipulate that "other" dataset. Could you please confirm if I
>> understood it correctly?
>
> Correct.
>
> You need the data in the root of the jail to boot, if you then attribute
> this dataset to the jail, it will vanish until "zfs mount -a" is run (rc
> script inside the jail). As it will vanish during the boot of the jail
> (if added automatically), the rc script to mount all datasets can not be
> found.

[...]

>> I think what you are trying to tell here is, unless and until that
>> "vanished" dataset is put to use (mounted) from inside the jail, it
>> will remain vanished/unusable from the host itself; however, once that
>> dataset is put to use, the host system should be able to "see" and
>> maybe even work on that dataset. Could you please confirm if I
>> understood you correctly?
>
> Correct.
>
> A sub-dataset which is not needed to boot, or a dataset not within the
> subtree of the jail (and not needed to boot) can be used.

Thank you for this information! If it is somewhere in the docs it is 
well hidden to me :)

Miroslav Lachman