AHCI driver and static device names

Rob lists at midsummerdream.org
Wed Dec 14 21:20:13 UTC 2011

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?


On 12/4/11 4:28 AM, perryh at pluto.rain.com wrote:
> CyberLeo Kitsana<cyberleo at 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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