On Thu, 3 Oct 2002, Bakul Shah wrote:
> > It was desired, and was sort of promised.
>
> I never understood why removal of block devices was allowed
> in the first place. phk's reasons don't seem strong enough
> to any unix wizard I have talked to. Did the majority of the
> core really think the change was warranted? Removing
> compatibility when the change _doesn't_ bring a *substantial*
> improvement doesn't seem right.
He had some backing, for example Kirk made a good argument for removing
them. The arguments about not being able to do devfs and geom without
removing them are of course specious as it can and was done before
by others.
>
> How hard would it be to bring back block devices without GEOM?
Even WITH geom it would be possible.
>
> Is there a write up somewhere on what GEOM is and its
> benefits? I'd hate to see it become the default without
> understanding it (and no, reading source code doesn't do it).
The concept is good.
One provides a stacking system for disk geometries wand layouts
where the upper interface is the same as that provided by the actual
disk.
Using devfs, one can export the 'top suface' of the stack as accessible
devices. Theoretically the latyers can apply themselvces as a device is
recognised and each layer type 'probes' the device to figure
out it it belongs there. It's not rocket science as far as an idea goes.
The trick is in the implementation. Locking and access control of
parts gets quite tricky.
for a similar idea look in the cvs tree for the
now removed 'slice' code that did teh same thing. /sys/dev/slice
It supported black and character device nodes for each partition.
>
> Thanks!
>
> -- bakul
>
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