Haudy Kazemi wrote:
Hello,
I recently asked myself this question: Is it possible to unset ZFS
properties? Or reset one to its default state without looking up what
that default state is?
I believe the answer is yes, via the zfs inherit command (I haven't
verified yet, but I think a case could be made to add functionality to
the zfs set command...or the documentation...to make this clearer.)
An example:
You have a pool named tank.
You have created a filesystem called 'home' and it has a child
filesystem called 'smith'.
You run: zfs set compression=on tank/home
which turns on compression on the 'home' filesystem (it is a local
property) and on the 'smith' filesystem (as an inherited property).
(You inspect the properties with 'zfs get'.)
You then run: zfs set compression=on tank/home/smith
which makes compression on the 'smith' filesystem also be a local property.
At this point you decide you would rather that the compression property
for filesystem 'smith' be inherited after all, not be a local property
anymore.
You run:
zfs set compression=off tank/home/smith
but that doesn't unset the compression setting for filesystem 'smith',
it just overrides the inheritance of compression=on (as expected).
So how to unset/reset?
zfs inherit compression tank/home/smith
*****
In short, I think an alias for 'zfs inherit' could be added to 'zfs set'
to make it more clear to those of us still new to ZFS. Either that, or
add some additional pointers in the Properties documentation that the
set command can't unset/reset properties.
That would to me be confusing it would also complicate the code quite a
lot because now the action would be part of the value for a different
subcommand. It also won't work at all for some properties, in
particular what if you have a hostname called "inherit" that is going to
be very confusing for the share* properties.
If there is an issue here I believe we should first trying and resolve
it with documentation changes.
--
Darren J Moffat
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