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Message-ID: <18048.35410.896207.686311@notabene.brown>
Date: Tue, 26 Jun 2007 13:38:58 +1000
From: Neil Brown <neilb@...e.de>
To: Graeme Sheppard <nodes@...lion.net>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: Patent or not patent a new idea
On Tuesday June 26, nodes@...lion.net wrote:
> Neil Brown wrote:
> >
> > Sounds a lot like "RAIF" - ask google for details.
>
> I did not know about RAIF. RAIF "merges" separate filesystems? That is a
> good idea in itself.
>
> My idea is for driver that provides a filesystem from image files it
> controls. Because it knows these resources it uses access in tandem to
> attain performance.
???
(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.
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'.
So I still cannot see anything particularly new. What am I missing?
NeilBrown
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