SPAM: Re: ZFS root, error 2 when mounting root

dweimer dweimer at
Mon Feb 25 17:04:00 UTC 2013

On 02/25/2013 10:00 am, bw wrote:
>>> That was my understanding, too, but the instructions on the wiki say 
>>> there's no need to copy the cache file. In fact, there is no cache 
>>> file to copy, since the pool is created with
>>> zpool create -o altroot=/mnt -O canmount=off zroot mirror 
>>> /dev/gpt/g0zfs /dev/gpt/g1zfs
>>> No cache file. The wiki article was changed recently to eliminate 
>>> that part, the message on the wiki is: "Fix so that the default 
>>> instructions does not install data directly to the zroot pool. 
>>> Simplify instructions regarding cache files, they are no longer 
>>> needed. Fixes and cleanups."
>>> Either the instructions are wrong, or something in my script is. I 
>>> assume it's my script.
>> 	The instructions noted above are now INCORRECT for 9.0 (I have not 
>> tried this with 9.1 yet) as you MUST manually put the zpool.cache file 
>> in place for it to work correctly (I tried a couple different 
>> variations when I first setup my systems a few months ago and learned 
>> this the hard way :-) I have *lost* of experience with ZFS under 
>> Solaris 10 but am relatively new (about a year) to FreeBSD.
> I tried it on 9.1, failed to specify.

There is a change coming down through the stable or current channel, 
that doesn't require the zpool.cache file.  But I don't believe that it 
has made it's to any of the releases.  I haven't been able to track down 
the original message yet, but here is some of the relevant text from a 
reply on the freebsd-stable mailing list, the subject of the thread is 
"[HEADSUP] zfs root pool mounting", if you chose to search for it on 
your own.

>>> on 28/11/2012 20:35 Andriy Gapon said the following:
>>>> 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.

    Dean E. Weimer

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