kern/166566: [zfs] zfs split renders 2 disk (MBR based) mirror unbootable

[Andriy Gapon]

The following reply was made to PR kern/166566; it has been noted by GNATS.

From: Andriy Gapon <avg at FreeBSD.org>
To: hartzell at alerce.com
Cc: bug-followup at FreeBSD.org
Subject: Re: kern/166566: [zfs] zfs split renders 2 disk (MBR based) mirror
 unbootable
Date: Thu, 28 Jun 2012 09:48:26 +0300

 on 28/06/2012 00:53 George Hartzell said the following:
 > Andriy Gapon writes:
 >  > on 27/06/2012 00:38 George Hartzell said the following:
 >  > > currdev does not seem to have any effect, it looks like something else
 >  > > is being used to find the initial zfs pool(s).
 >  > 
 >  > Just a note that currdev would not affect the order of the pools in lsdev
 >  > output.  It should affect from which pool the zpool.cache is loaded.
 >  > 
 >  > Ah!  You probably need to issue unload command as well.  I keep forgetting that
 >  > in default configuration loader loads up stuff before presenting its menu.  I've
 >  > changed my loader.rc, so that nothing is loaded before the menu.
 >  > 
 >  > But, yes, the best course of action seems to be to fix up zsplitroot right after
 >  > splitting it off.
 >  > 
 >  > Thank you for your persistence in testing and debugging!
 > 
 > I thought the following would work, but it does not.
 > 
 >   zpool split -R /zsplitroot zroot zsplitroot
 >   zpool status  # shows both pools.
 >   mount -t zfs zsplitroot /zsplitroot  # my zfs stuff doesn't auto mount
 >   cp /boot/zfs/zpool.cache /zsplitroot/boot/zfs
 >   perl -pi.bak -e 's|zfs:zroot|zfs:zsplitroot|' /zsplitroot/boot/loader.conf
 >   umount /zsplitroot
 > 
 > It fails to mount zsplitroot.  Worse, setting vfs.zfs.debug=1 results
 > in no additional output, just that the error is number 2.
 > 
 > Any idea what I'm missing?
 
 
 /boot/zfs/zpool.cache after split contains only information about zroot.  Thus
 it's kind of useless on zsplitroot.
 I think that you need to do zpool import -R ... -c ... zsplitroot and copy the
 proper cache file.
 
 -- 
 Andriy Gapon