Seek-Efficient I/O Optimization in Single Failure Recovery for XOR-coded Storage Systems

Abstract

Erasure coding provides an effective means for storage systems to protect against disk failures with low redundancy. One important objective for erasure-coded storage systems is to speed up single disk failure recovery. Previous studies reduce the amount of data read for recovery by reading only a small subset of data, but their approaches often incur high disk seeks, which may negate the resulting recovery performance. We propose SIOR, a seek-efficient I/O recovery algorithm for single disk failures. SIOR carefully balances the trade-off between the amount of data read and the number of disk seeks by considering the data layout at the multi-stripe level. It then greedily determines the data to read for recovery using Tabu search. Experiments show that SIOR achieves similar performance to the brute-force enumeration method while keeping high search efficiency. Also, SIOR reduces 31.8%~65.1% of disk seeks during recovery and provides up to 186.8% recovery speed improvement, when compared to a state-of-the-art greedy recovery approach.