Re: Patent or not patent a new idea

[Graeme Sheppard]

Neil Brown wrote:
> ???
> (reads original description in more detail).
>
> So... the filesystem images are identical in both copies, and the
> "interesting" bit is that the image is just a file on some filesystem.
>
> So could I implement your idea by:
>
>   dd if=/dev/zero of=/1/bigfile count=lotsandlots
>   dd if=/dev/zero of=/2/bigfile count=lotsandlots
>   losetup /dev/loop1 /1/bigfile
>   losetup /dev/loop2 /2/bigfile
>   mdadm -C /dev/md0 --level=raid1 --raid-disks=2 /dev/loop1 /dev/loop2
>   mkfs /dev/md0
>   mount /dev/md2 /space
>
> ??
>
> Why would you bother?  Well, I do it a lot of code testing, but I
> would be hard pressed to make a case for that sort of config in
> production.

Thanks for the brief howto there. I'll install the mdadm suite and
experiment. It seems like a userspace driver?

> You said:
> >  1) the disks need
> >    not be the same size or from the same manufacturer; 2) the supporting code
> >    would be cross-platform.
>
> md/raid already works happily with different sized drives from
> different manufacturers (for raid1, it only uses as much space as the smaller
> drive provides, For raid0 it uses it all).
> I don't know what you mean by '2'.

2 meant in the way that a driver for a PC raid card is not much use on
a Sparc.

> So I still cannot see anything particularly new.  What am I missing?

I think it's what I missed. Thanks for the heads-up. If the above is
a good technique it could suit me well.

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