Can't mountroot from ZFS pool

krad kraduk at
Tue Jan 19 17:07:57 UTC 2010

2010/1/19 Steve Bertrand <steve at>

> krad wrote:
> >
> >
> > 2010/1/11 Steve Bertrand <steve at <mailto:steve at>>
> >
> >     All,
> >
> >     I've successfully upgraded the disks in my ZFS backup server, and can
> >     import/mount the pool properly.
> >
> >     However, I designed this box originally so that it mounts / from
> >     zfs:storage after booting from a USB stick.
> >
> >     After the upgrade of the disks, I'm stuck at a mountroot prompt when
> I
> >     attempt to boot the system with the original USB /boot key.
> >
> >     Can someone inform me how to find the / filesystem at the mountroot
> >     prompt? If not, is there *any* way to boot the system normally from
> >     another medium, and then 'reload' the system with the ZFS / after its
> >     been mounted so that the system functions as designed (ie. cron
> >     works etc)?
> > did you export the pool at all before rebooting it?
> Yes, I did.
> I just finally got it resolved :)
> It appears as though by importing the zpool onto another system
> obsoleted the cache file on the original USB /boot disk.
> I exported, then imported the pool on the secondary system, then copied
> the cache file into the /boot/zfs directory on my original boot medium.
> Things are now working again, and I have all of my new storage and
> original data in place!
> Thanks for all the help!
> Steve

Its an easy mistake to make. People think exporting a pool is  the same as
unmounting but it isn't really, and its kind of difficult to explain why
(unless ur an uber guru)

One thing for sure is that the hostid of the system is stored in to the
zpool somewhere as is the state of it. This also has to match the
zpool.cache files details. The reason for this is probably largely to do
with sun clustering, where a pool on a particular lun may be visible to many
nodes in the cluster, but only one having it currently imported and the
subsequent file systems mounted.

Hmm, why does it always sound so clunky when I try to explain it 8/

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