How to mirror the FreeBSD OS on two disks

[Warren Block]

On Wed, 11 Jul 2012, Kaya Saman wrote:

> On Wed, Jul 11, 2012 at 10:18 AM, miles kuo <miles.kuo at gmail.com> wrote:
>> Hi all,
>>
>> I have two SAS disks for the FreeBSD install. I want to install the freeBSD
>> on one disk and mirror to another disk. Just like the AIX Mirror.
>>
>> Any changes will sync between the two disks. And if  one disk crashed or
>> disconnected, the OS could continue running on another disk.
>>
>> Does the FreeBSD support the disk mirror? How to implement it?
>
> I am no expert at this however a quick Google search comes up with:
>
> http://www.freebsd.org/doc/handbook/geom-mirror.html

The procedure shown there produces a mirror that will not boot on 
FreeBSD 9.  The release notes mention a workaround:
http://www.freebsd.org/releases/9.0R/relnotes-detailed.html#AEN1277

(There's work under way to fix that chapter.)