Progressive Parity-Based Hardening of Data Stores

We propose the use of parity-based redundant data layouts of increasing reliability as a means to progressively harden data archives. We evaluate the reliability of two such layouts and demonstrate how moving to layouts of higher parity degree offers a mechanism to progressively and dramatically increase the reliability of a multi-device data store. Specifically we propose that a data archive can be migrated to progressively more reliable layouts as the data ages, trading limited (and likely unrealized) increases in update costs for increased reliability. Our parity-based schemes are drawn from SSPiRAL (survivable storage using parity in redundant array layouts) that offer capacity efficiency equivalent to a straightforward mirroring arrangement. Our analysis shows our proposed schemes would utilize no additional physical resources and result in improvements to mean time to data loss of four to seven orders of magnitude.