Construction of Partial MDS (PMDS) and Sector-Disk (SD) Codes with Two   Global Parity Symbols
  Partial MDS (PMDS) codes are erasure codes combining local (row) correction with global additional correction of entries, while Sector-Disk (SD) codes are erasure codes that address the mixed failure mode of current RAID systems. It has been an open problem to construct general codes that have the PMDS and the SD properties, and previous work has relied on Monte-Carlo searches. In this paper, we present a general construction that addresses the case of any number of failed disks and in addition, two erased sectors. The construction requires a modest field size. This result generalizes previous constructions extending RAID~5 and RAID~6. 
Mario Blaum, James S. Plank, Moshe Schwartz, Eitan Yaakobi
cs.IT math.IT