Re: Is this enough for us to have triple-parity RAID?

[Piergiorgio Sartor <piergiorgio.sartor@xxxxxxxx>]

Hi David,

> My current state is that I've got theory worked out and written up -
> not just for triple parity, but for more parities as well.  For some
> of it, I've got Python code to test and verify the maths.  It turns
> out that triple parity can work well - but for quad parity the limit
> is 21 data disks (using generators 2, 4, and 8), or up to 33 (using
> for example 0x07, 0x35 and 0x8b as generators).  Realistically, I
> think triple parity is the limit for practical implementations.

Why is that? An RS code (255,251) should be possible, like
it is a (255,223). What's the limitation?
I'm sure there is even a "RAID-96", which is (96,64).

My wild guess would be that the generators must be chosen
in some way.

Have you had a look at the "par2" code? That seems to be
capable of doing a parametric RS, even if in 16bit words.

bye,

-- 

piergiorgio
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html