Assessing the performance of erasure codes in the wide-area

The problem of efficiently retrieving a file that has been broken into blocks and distributed across the wide-area pervades applications that utilize Grid, peer-to-peer, and distributed file systems. While the use of erasure codes to improve the fault-tolerance and performance of wide-area file systems has been explored, there has been little work that assesses the performance and quantifies the impact of modifying various parameters. This paper performs such an assessment. We modify our previously defined framework for studying replication in the wide-area [6] to include both Reed-Solomon and Low-Density Parity-Check (LDPC) erasure codes. We then use this framework to compare Reed-Solomon and LDPC erasure codes in three wide-area, distributed settings. We conclude that although LDPC codes have an advantage over Reed-Solomon codes in terms of decoding cost, this advantage does not always translate to the best overall performance in wide-area storage situations. 1