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To: freebsd-questions@freebsd.org
From: Grzegorz Junka <list1@gjunka.com>
Subject: Installing zfsboot on FreeBSD 11.0
Message-ID: <28892c88-a58b-4090-84ad-8e6f240bba3f@gjunka.com>
Date: Sun, 29 Jan 2017 13:57:37 +0000
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In the description of the loader

https://www.freebsd.org/cgi/man.cgi?query=zfsboot&sektion=8

we can read that if the drive is currently in use, the GEOM safety will 
prevent writes and must be disabled before running the above commands:

        sysctl kern.geom.debugflags=0x10

This worked fine on 10.3, but doesn't seem to work on FreeBSD 11.0:

root@crayon2:~ # sysctl kern.geom.debugflags=0x10
kern.geom.debugflags: 16 -> 16
root@crayon2:~ # dd if=/boot/zfsboot of=/dev/ada0s1a skip=1 seek=1024
dd: /dev/ada0s1a: Operation not permitted

Any suggestions?