Highly Reliable Two-Dimensional RAID Arrays for Archival Storage
The authors present a two-dimensional RAID architecture that is specifically tailored to the needs of archival storage systems. Their proposal starts with a fairly conventional two-dimensional RAID architecture where each disk belongs to exactly one horizontal and one vertical RAID level 4 stripe. Once the array has been populated, they add a superparity device that contains the exclusive OR of all the contents of all horizontal -or vertical-parity disks. The new organization tolerates all triple disk failures and nearly all quadruple and quintuple disk failures.