ZFS 'mount error 5' hits production server

[Michael Schmiedgen]

On 04.12.2014 12:52, Steven Hartland wrote:
>
>> Please tell if I should provide some more information.
> Did you try converting from tank from legacy to standard mount point?
>

I already tried, but I cannot, because it is mounted.

# zfs set mountpoint=/ tank
error: cannot unmount / (...or something)

Or is there another way to do this?

Thanks,
   Michael