[HEADSUP] zfs root pool mounting

[Daniel Braniss]

> 
> Recently some changes were made to how a root pool is opened for root filesystem
> mounting.  Previously the root pool had to be present in zpool.cache.  Now it is
> automatically discovered by probing available GEOM providers.
> The new scheme is believed to be more flexible.  For example, it allows to prepare
> a new root pool at one system, then export it and then boot from it on a new
> system without doing any extra/magical steps with zpool.cache.  It could also be
> convenient after zpool split and in some other situations.
> 
> The change was introduced via multiple commits, the latest relevant revision in
> head is r243502.  The changes are partially MFC-ed, the remaining parts are
> scheduled to be MFC-ed soon.
> 
> I have received a report that the change caused a problem with booting on at least
> one system.  The problem has been identified as an issue in local environment and
> has been fixed.  Please read on to see if you might be affected when you upgrade,
> so that you can avoid any unnecessary surprises.
> 
> You might be affected if you ever had a pool named the same as your current root
> pool.  And you still have any disks connected to your system that belonged to that
> pool (in whole or via some partitions).  And that pool was never properly
> destroyed using zpool destroy, but merely abandoned (its disks
> re-purposed/re-partitioned/reused).
> 
> If all of the above are true, then I recommend that you run 'zdb -l <disk>' for
> all suspect disks and their partitions (or just all disks and partitions).  If
> this command reports at least one valid ZFS label for a disk or a partition that
> do not belong to any current pool, then the problem may affect you.
> 
> The best course is to remove the offending labels.
> 
> If you are affected, please follow up to this email.

GREATE!!!!
in a diskless environment, /boot is read only, and the zpool.cache issue
has been bothering me ever since, there was no way (and I tried) to re route it.

thanks,
	danny