On Wed, Sep 15, 15:55, Michael Sallaway wrote: > As a sort-of follow up question, would anyone know if the data size of > a Q calculation affects the result at all? eg. if I do a 64kb Q > calculation on 10 drives of data, would that be the same as doing 16x > 4kb Q calculations on sequential blocks of the same data, then > concatenating it together? (I can't remember what that operation > property is called....?) Yes, the result would be the same. In fact, byte n of Q depends only on byte n of the 10/16 data drives. > I've been reading the maths of RAID6 PDF > (http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf), but I'm a > bit too rusty to understand Galois fields, and if the data size > matters. I presume the data ordering is also critical for a Q > calculation, correct? (eg. drives have to be d0 -> d10 in order, not > just random). Right, order matters. > And, in contrast, for the P calculations, data size and input order > makes no difference, correct? (since it's just a simple bitwise XOR of > all the inputs). Also correct. Andre -- The only person who always got his work done by Friday was Robinson Crusoe
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