Gmirror + gpart corruption on 9.3-PRE

[Dave Hayes]

On 07/24/2014 21:04, Warren Block wrote:
> I believe that GPT tables somehow work only on the drive level.  That
> is, the GPT partitioning created inside the mirror actually overwrites
> the existing one on the drive.  As odd as it sounds, I think this is
> intentional: GPT tables are only supposed to be at the beginning and end
> of a physical drive.  But I'm also not the one to explain it.
>
> However, the attempted GPT partitioning inside the mirrors is not needed
> and can be left out.

I did this because newfs seemed to corrupt the partition table if I did 
not do this.

> GPT tests got more strict at some point.  Maybe the rules for GPT tables
> did also.

That sounds like the simplest explanation.

> For reference, here is my article on mirroring GPT disk partitions.  I
> do not recommend it.  (Consider the head contention when multiple
> mirrors on the same drive attempt to rebuild.  Or disable automatic
> rebuilding, but then it's going to be unpleasant in an emergency.)

Since I'm only having two mirrors, would it be better to disable just 
the automatic rebuilding on the swap space?

Would graid be better to use to achieve a mirrored volume?

> For drives under 2TB, use MBR and bsdlabels, as ugly as it is.  The
> recently-rewritten Handbook procedure shows the right way to do it,
> including alignment:
> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-mirror.html

Yeah, I'd do this except there will come a day when 2TB drives cannot be 
found, and I have a significant history of having machines more than 6-7 
years old.

Sadly, I cannot use ZFS in this circumstance due to heavy memory 
requirements of what the machine will be used for.
-- 
Dave Hayes - Consultant - Altadena CA, USA - dave at jetcafe.org
 >>>> *The opinions expressed above are entirely my own* <<<<

There are only 10 kinds of people that understand binary
                          - those that do, and those that don't.