freebsd-update from 8.4 to 9.3 causes gmirror to disappear -- HELP!

Warren Block wblock at
Thu Jun 25 22:33:05 UTC 2015

On Thu, 25 Jun 2015, wfdudley wrote:

> I've been running 8.4 STABLE for a while, but decided to try to use
> freebsd-update to move to 9.3
> I have a pair of 2TB drives in a gmirror.  Works fine.
> I used svn to pull the 8.4 RELEASE source, and built myself an 8.4 RELEASE
> system.
> Then, I followed the instructions here:
> And after the first reboot in to the 9.3 kernel, my gmirror is GONE.
> This is ALL MY DATA, and the freebsd-update database
> (/var/db/freebsd-update).
> After discovering that the mirror was GONE, I did this:
> sysctl kern.geom.debugflags=17
> gmirror label -vb round-robin gm0 /dev/ad14

That turns off the safety and creates (writes) a new mirror on one 
drive.  Please stop writing to those drives and check your backups.  If 
you are lucky, the data is still present on the second drive.

> Which is how I configured the mirror initially (from this
> post).

The Handbook has a full section on creating mirrors, but that is not 
what is needed.  Instead, the existing mirror just needs to be mounted.

The problem might be this:

You do not mention what you mean by the mirror being "gone".  Was there 
an error message?  It might be as simple as editing /etc/fstab.

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