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

["H. Peter Anvin" <hpa@xxxxxxxxx>]

On 04/17/2012 01:18 PM, David Brown wrote:
> 
> For quad parity, we can try g3 = 8 as the obvious next choice in the
> pattern.  Unfortunately, we start hitting conflicts.  To recover missing
> data, we have to solve multiple simultaneous equations over G(2⁸), whose
> coefficients depend on the index numbers of the missing disks.  With
> parity generators (1, 2, 4, 8), some of these combinations of missing
> disk indexes lead to insoluble equations when you have more that 21 disks.
> 

That is because 255 = 3*5*17... this means {02}^3 = {08} is not a generator.

	-hpa

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