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Date: Fri, 16 Nov 2012 17:45:07 +0200
From: Andriy Gapon <avg@FreeBSD.org>
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To: Guido Falsi <mad@madpilot.net>, Bartosz Stec <bartosz.stec@it4pro.pl>
Subject: problem booting to multi-vdev root pool [Was: kern/150503: [zfs]
 ZFS disks are UNAVAIL and corrupted after reboot]
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on 13/11/2012 18:16 Guido Falsi said the following:
> My idea, but is just a speculation, i could be very wrong, is that the geom
> tasting code has some problem with multiple vdev root pools.

Guido,

you are absolutely correct.  The code for reconstructing/tasting a root pool
configuration is a modified upstream code, so it inherited a limitation from it:
the support for only a single top-level vdev in a root pool.
I have an idea how to add the missing support, but it turned out not to be
something that I can hack together in couple of hours.

So, instead I wrote the following patch that should fall back to using a root pool
configuration from zpool.cache (if it's present there) for a multi-vdev root pool:
http://people.freebsd.org/~avg/zfs-spa-multi_vdev_root_fallback.diff

The patch also fixes a minor (single-time) memory leak.

Guido, Bartosz,
could you please test the patch?

Apologies for the breakage.

-- 
Andriy Gapon