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#67 Code used in PAR2 is not Reed-Solomon

open
nobody
par (10)
5
2008-11-03
2008-11-03
Petr Matas
No

The code used in PAR2 is not a Reed-Solomon code, nor it is MDS (Minimum Distance Separable). This means that repair will fail in some cases.

For example, if you try to repair three blocks (the block number 2, 48 and 237, counted from zero) using three recovery blocks (recovery block number 1, 2 and 4, counted from zero), the process will always fail with "Reed Solomon computation error" regardless of the number of recovery blocks availabe (see attached screenshot). You have to damage one more block to get a successful repair in this case.

Discussion

  • Petr Matas

    Petr Matas - 2008-11-03

    Code failure

     
  • Petr Matas

    Petr Matas - 2008-11-03

    Oh, I messed up the expansion of MDS acronym. It means Maximum Distance Separable code.

     

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