Mirroring the root disk of already installed machine

[Wilko Bulte]

On Fri, Sep 08, 2006 at 09:29:00AM -0400, Mike Meyer wrote..
> In <20060908100337.73c0c88d.vlady at gbservices.biz>, Vladimir Terziev <vlady at gbservices.biz> typed:
> > 	i have a machine running FreeBSD 5.4 . It has 2 HDDs. Recently the non-root HDD failed and lost all the data on it. Since the machine is working 24/7 i want to mirror its root disk (this one with the OS on it) in order to prevent a severe downtime and data loss.
> > 
> > 	Is there a safe way to do the above using gmirror ?
> 
> Yes. I started doing it on FreeBSD 5.5. It's pretty simple: shut down
> to single user. Create a mirror with your root disk in it. Edit
> /etc/hosts to change the device name from ad* to

/etc/fstab

> mirror/*. Reboot. Once you're back up, add the second disk to the
> mirror. If you want exact instructions, consult google. The tricky
> part is creating the initial mirror on a mounted file system - you
> have to toggle a sysctl (I think that's what it was) to do that. Some
> directions include that; others recommend you boot on a recovery CD to
> create the mirror initially.
> 
> BTW, this probably should have gone to -questions.
> 
> 	<mike
> -- 
> Mike Meyer <mwm at mired.org>		http://www.mired.org/consulting.html
> Independent Network/Unix/Perforce consultant, email for more information.
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-- 
Wilko Bulte				wilko at FreeBSD.org