Newbie gmirror questions

[Mike Clarke]

On Sunday 17 January 2010, Matthew Seaman wrote:

> Mike Clarke wrote:
> > Actually I was more concerned about what happens when I boot into
> > another OS like Windows or Linux on one of the spare slices - I'm
> > assuming that I have to apply gmirror to the whole disk rather than
> > just selected slices?
>
> You can't do this.  gmirror is FreeBSD specific, and other OSes can't
> deal with it.  You can take your two drives, partition them (fdisk)
> and then create a gmirror across the slices you assign to FreeBSD.

This will make things a lot easier for me. I think all the examples of 
gmirror I've seen used things like /dev/da0 as the provider in label 
commands so I assumed that I had to use the whole physical disk but if 
I can mirror individual slices then I have much more flexibility.

My motherboard has a UDMA133 controller for ata0 & ata1 (which I don't 
use) and 2 SATA controllers for ata2 to ata5 so with my 2 SATA drives 
spread between the controllers on channels 2 & 4 I could have something 
like /dev/mirror/gm1 provided by /dev/ad2s1 & /dev/ad4s1 
and /dev/mirror/gm2 provided by /dev/ad2s2 & /dev/ad4s2 for a couple of 
FreeBSD systems. That will leave me with 2 spare slices on each drive 
for other purposes. Any Windows or Linux stuff I put on tends to be 
mainly experimental and less long term than my FreeBSD system so don't 
really need the resilience of being mirrored.

-- 
Mike Clarke