LESS is More for I/O-Efficient Repairs in Erasure-Coded Storage

I/O efficiency is critical for erasure-coded repair performance in modern distributed storage. We propose LESS, a family of repair-friendly erasure code constructions that reduces both the amount of data accessed and the number of I/O seeks in single-block repairs, while ensuring balanced reductions across blocks. LESS layers multiple extended sub-stripes formed by widely deployed Reed-Solomon coding, and is configurable to balance the trade-off between the amount of data accessed and I/O seeks. Evaluation shows that LESS on HDFS reduces both single-block repair and full-node recovery times compared to state-of-the-art I/O-optimal erasure codes.