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Date:      Sun, 17 Jan 2010 21:22:14 +0000
From:      Mike Clarke <>
Cc:        Pieter de Goeje <>
Subject:   Re: Newbie gmirror questions
Message-ID:  <>
In-Reply-To: <>
References:  <> <> <>

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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. =A0gmirror is FreeBSD specific, and other OSes can't
> deal with it. =A0You 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=20
gmirror I've seen used things like /dev/da0 as the provider in label=20
commands so I assumed that I had to use the whole physical disk but if=20
I can mirror individual slices then I have much more flexibility.

My motherboard has a UDMA133 controller for ata0 & ata1 (which I don't=20
use) and 2 SATA controllers for ata2 to ata5 so with my 2 SATA drives=20
spread between the controllers on channels 2 & 4 I could have something=20
like /dev/mirror/gm1 provided by /dev/ad2s1 & /dev/ad4s1=20
and /dev/mirror/gm2 provided by /dev/ad2s2 & /dev/ad4s2 for a couple of=20
=46reeBSD systems. That will leave me with 2 spare slices on each drive=20
for other purposes. Any Windows or Linux stuff I put on tends to be=20
mainly experimental and less long term than my FreeBSD system so don't=20
really need the resilience of being mirrored.

Mike Clarke

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