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Date:      Wed, 14 Dec 2011 15:20:08 -0600
From:      Rob <lists@midsummerdream.org>
To:        perryh@pluto.rain.com
Cc:        cyberleo@cyberleo.net, ryallsd@gmail.com, freebsd-questions@freebsd.org
Subject:   Re: AHCI driver and static device names
Message-ID:  <4EE91308.8050300@midsummerdream.org>
In-Reply-To: <4edb4b48.LvOhZvvsP1inJeps%perryh@pluto.rain.com>
References:  <4ED98E9F.9010401@midsummerdream.org> <CAN3mi_2u%2BHwFf3m%2BxvsNncfNpj_rFp94xjAv%2Bf0eFT7c4a%2B8Tg@mail.gmail.com> <4EDA489B.9060503@midsummerdream.org> <4EDA56A3.6090108@cyberleo.net> <4edb4b48.LvOhZvvsP1inJeps%perryh@pluto.rain.com>

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Can glabels, gpt, and zfs all work together?  I have a system where I 
have disks with 4 gpt partitions. Partitions 2 and 3 are part of gmirror 
arrays, and partition 4 is part of a zfs pool.  glabel says it writes to 
the end of the partition, which I believe zfs also writes to doesn't it?

Rob

On 12/4/11 4:28 AM, perryh@pluto.rain.com wrote:
> CyberLeo Kitsana<cyberleo@cyberleo.net>  wrote:
>
>> You cannot combine GPT with glabel (or any other geom class
>> that writes data to the first or last 34 sectors of a disk,
>> like gmirror) due to layout conflicts.
>
> This is overstated.  Since a GPT ordinarily is intended to be booted
> from, and so must be recognized by the BIOS, it must be written
> directly on the actual drive -- the "rank 1 provider" in GEOM terms
> -- because that is the only way for the GPT metadata to be located
> where the BIOS expects to find it (at both the beginning and the end
> of the drive).
>
> It is, however, possible to combine GPT with gmirror, gjournal,
> etc. by using GPT partitions, rather than drives, as providers
> for the other geoms.  For example, create a mirror from ad0p1
> and ad2p1 rather than from ad0 and ad2.  Similarly, it "should"
> be possible to glabel a GPT partition -- although this seems
> unlikely to be useful in practice since GPT provides its own
> labelling scheme.
>
>



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