Read-Only RAID-5 on DVD? :-)

[Daniel Carrera]

On Mon, 2006-03-07 at 10:56 +1000, James Gray wrote:
> If it's not sequential, it
> wont work. RAID5 is non-sequential.  Game over.

Maybe you can expand on how RAID-5 is not sequential. When I read the
OP's post my first reaction was that it couldn't possibly work, but here
is a convoluted thought:

* Start making 3 raw images: (A, B, C)
  - Put a block in A, a block in B and the parity in C
  - Put a block in A, a block in C and the parity in B
  ...

You get the idea. Essentially a "RAID 5", except that you are writing
the blocks to some on-disk file - would probably have to be some other
disk, not the one you are backing up...

* Then make an ISO of each of those images and burn them.


This would, at least in theory, have the RAID-5 property that the loss
of any one would not cause data loss. Now, I have no idea how you could
actually create these raw images in the first place (I'm not sure it's
possible) or how I could recover them later. So I definitely think that
this "RAID DVD" is unworkable with current systems. But I wonder if what
I described above is theoretically possible.

Cheers,
Daniel.
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