[RFC] Remove requirement of alignment to track from MBR scheme

[Marcel Moolenaar]

On May 25, 2011, at 8:12 AM, Andriy Gapon wrote:

> on 24/05/2011 21:12 Marcel Moolenaar said the following:
>> With respect to the creation:
>> 
>> Since out synthesized geometry is not necessarily the same
>> as other OSes, we could opt to synthesize a geometry that
>> has a track size (= sectors/track) that is a multiple of 8
>> (to play nice with 4K sectors), and/or take the stripe
>> size of the underlying GEOM into account. This fundamentally
>> doesn't change a thing for MBR, but has the side effect of
>> achieving some of the goals *and* automatically works for
>> EBR as well.
>> 
>> Thus: rather than hack MBR and forgetting about EBR and other
>> schemes, maybe we only have to tweak the geometry synthesis
>> to give people what they want without going over board. 
> 
> I don't think that currently we do synthesize any geometry in kernel.
> I think that we just whatever BIOS/firmware/etc provides to us in some way.

Yes, we do. gpart makes sure that there's always a geometry
and it adjusts the geometry based on information obtained
from schemes. The geometry given by geom_disk (= ad or da)
is typically the starting point. md does not have geometry
information, causing certain tools to work less well.

-- 
Marcel Moolenaar
xcllnt at mac.com