Re: [discuss] Cannot receive older ZFS dumps

["Joshua M. Clulow" <josh@sysmgr.org>]

On Thu, 1 Aug 2024 at 05:27, Udo Grabowski (IMK) <udo.grabowski@kit.edu> wrote:
> On 01/08/2024 12:53, Toomas Soome via illumos-discuss wrote:
> > Since we virtually do not develop zfs, it is rather hard to say, but it does sound like bug.

I don't know what this means, but I would like to make it very clear:
we, the illumos project, maintain all of the code in the gate.  This
includes ZFS.  If you've found something that used to work and doesn't
work anymore, that's definitely a bug -- please report it, with as
much diagnostic and debugging information as you can gather.

> >> Is this a bug or are "non-feature" dumps in general not importable
> >> on "feature"-zpools ?

I don't think any regression like that is intentional.  If we make an
intentional decision like that, the tool should print a crisp error
that the operator can understand which describes the situation -- so
even if it isn't intended to work (definitely not clear that this is
the case), the absence of a crisp failure and a helpful error message
would be, on its own, a bug.

> Did some more testing, could also import it on an 8 years old pool
> (illumos-a90d75b) with all the features (known at that time) active or enabled:
> Maybe one of that is to blame for the incompatibility, or it's a completely
> different bug. The error appears near the end of the zfs receive.

I think you'll probably need to use DTrace to find out where the error
is originating.  Presumably something in the kernel is validating the
incoming stream records in a new way, which might well be too strict
or just wrong in some way.


Cheers.

-- 
Joshua M. Clulow
http://blog.sysmgr.org