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Date: Thu, 18 Jan 2007 01:58:36 +0300
From: "Andrew Pantyukhin" <infofarmer@FreeBSD.org>
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References: <20070117103935.GC4018@genius.tao.org.uk>
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Cc: stable@freebsd.org, fs@freebsd.org
Subject: Re: gmirror disks vs partitions
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On 1/18/07, Scott Long <scottl@samsco.org> wrote:
> Andrew Pantyukhin wrote:
> > On 1/17/07, Josef Karthauser <joe@freebsd.org> wrote:
> >> A poll for opinions if I may?
> >>
> >> I've got a few gmirrors running on various machines, all of which
> >> pair up two drives at the physical level (i.e. mirror /dev/ad0s1
> >> with /dev/ad1s1).  Of course there are other ways of doing it to,
> >> like mirroring at the partition level, ie pairing /dev/ad0s1a with
> >> /dev/ad1s1a, /dev/ad0s1e with /dev/ad0s1e, etc.
> >>
> >> Apart from potentially avoiding a whole disk from being copied
> >> during a resync after a crash, are there any other advantages to
> >> using partition level mirroring instead of drive level mirroring?
> >
> > I can imagine people using partition-level raid to
> > implement a popular configuration:
> >
> > You divide a couple of identical drives proportionally
> > in two partitions each, place a couple of the first
> > partitions into gmirror and a couple of the second
> > ones into gstripe. This way you get both reliable and
> > fast storage with just two drives. Some strings are
> > attached.
>
> The head movement that this causes makes it a poor performer.  It is
> an option, but not a terribly popular one.

I hear many desktops and laptops nowadays (used to?)
come preconfigured this way.