Toward Efficient Repair for Wide-Stripe Erasure Coding With High Reliability

Abstract

Erasure coding is a common redundancy scheme to provide higher reliability with much lower storage overhead compared to replication. It prevents data loss due to failures but induces high repair costs. As data volumes grow exponentially, wide stripes are proposed for extreme storage savings. Wide-stripe erasure codes face the challenges of higher repair costs for single and multiple failures. Our extensive analysis shows that existing repair-efficient erasure codes, such as locally repairable codes (LRCs) and minimum storage regenerating (MSR) codes, are insufficient to meet all the requirements of wide stripes: low storage overhead, low repair cost for both single and multiple failures, and high reliability. In this article, we explore an alternative code scheme, locally repairable with zigzag code (LRZC), which combines the advantages of LRCs and zigzag codes. LRZC divides data blocks and global parity blocks into evenly sized local groups, and generates two local parity blocks by a zigzag code in each group. Under the limit of storage overhead of wide stripes, LRZC reduces the repair cost for single and multiple failures and provides higher reliability compared with existing wide-stripe codes. Experiments show that LRZC reduces the repair cost of single and multiple failures by up to 41.9% and 41.7% compared with the state-of-the-art LRCs.