We present the WEAVER codes, new families of simple highly fault tolerant XOR-based erasure codes for storage systems (with fault tolerance 12 in some cases). The design features of WEAVER codes are (a) placement of data and parity blocks on the same strip (so-called vertical codes) and (b) constrained parity in-degree (so parity computation costs are small). These codes are not maximum distance separable (MDS) but have optimal storage efficiency among all codes with constrained parity in-degree. Though applicable to RAID controller systems, the WEAVER codes are probably best suited in dRAID systems (distributed Redundant Arrangement of Independent Devices). In addition, these codes have other advantages over many erasure codes for storage systems.
By: James Lee Hafner
Published in: RJ10353 in 2005
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