Re: zpool import: "The pool cannot be imported due to damaged devices or data" but zpool status -x: "all pools are healthy" and zpool destroy: "no such pool"

[message chopped and butchered, don't follow the quotes, it's just to show
some bits together from different messages]

On Thu, Sep 16, 2021 at 3:54 PM Mark Millard via freebsd-current <
freebsd-current@freebsd.org> wrote:

> > > For reference, as things now are:
> > >
> > > # gpart show
> > > =>       40  937703008  nda0  GPT  (447G)
> > >          40     532480     1  efi  (260M)
> > >      532520       2008        - free -  (1.0M)
> > >      534528  937166848     2  freebsd-zfs  (447G)
> > >   937701376       1672        - free -  (836K)
> > > . . .
>


> > > So you just want to clean nda0p2 in order to reuse it?  Do "zpool
> labelclear -f /dev/nda0p2"
> > >
> >>
> >> I did not extract and show everything that I'd tried but
> >> there were examples of:
> >>
> >> # zpool labelclear -f /dev/nda0p2
> >> failed to clear label for /dev/nda0p2
>
> The start of the problem looked like (console context,
> so messages interlaced):
>
> # zpool create -O compress=lz4 -O atime=off -f -tzopt0 zpopt0 /dev/nvd0
> GEOM: nda0: the primary GPT table is corrupt or invalid.
> GEOM: nda0: using the secondary instead -- recovery strongly advised.
> cannot create 'zpopt0': no such pool or dataset
> # Sep 16 12:19:31 CA72_4c8G_ZFS ZFS[1111]: vdev problem, zpool=zopt0
> path=/dev/nvd0 type=ereport.fs.zfs.vdev.open_failed
>
> The GPT table was okay just prior to the command.
> So I recovered it.
>

It looks like you're trying to use a disk partition for a ZFS pool
(nda0p2), but then you turn around and use the entire drive (nvd0) for the
pool which clobbers the GPT.  You need to be consistent in using partitions
for all commands.  You're also mixing up your disk device nodes for the
different commands; while they are just different names for the same thing,
it's best to be consistent.

GEOM is built out of layers (or more precisely, "containers" as
it specifies a new start and end point on the disk), which is very
powerful.  But it's also very easy to make a mess of things when you start
accessing things outside of the layers.  :)  And ZFS labelclear option is
the nuclear option that tends to remove everything ZFS-related, and
everything GPT-related; although I've never seen it used on a partition
before, usually just the disk.

Best bet in this situation is to just zero out the entire disk (dd
if=/dev/zero of=/dev/nda0 bs=1M), and start over from scratch.  Create a
new GPT.  Create new partitions.  Use the specific partition with the
"zpool create" command.

-- 
Freddie Cash
fjwcash@gmail.com