Rethinking erasure codes for cloud file systems: minimizing I/O for recovery and degraded reads
Rethinking erasure codes for cloud file systems: minimizing I/O for recovery and degraded reads
复制标题
DOI：
--
复制
发表时间：
2012-02
期刊：
影响因子：
--
通讯作者：
O. Khan;R. Burns;J. Plank;William Pierce;Cheng Huang
中科院分区：
文献类型：
--
作者：
O. Khan;R. Burns;J. Plank;William Pierce;Cheng Huang
为了减少存储开销，云文件系统正在从复制过渡到擦除代码。这一过程揭示了评估不同编码方案性能的新维度：在恢复和执行降级读取时使用的数据量。我们提出了一种算法，它为任何基于异或的擦除码找到恢复所需的码字符号的最佳数目，并产生使用最少数据量的恢复时间表。我们根据这一标准区分了流行的擦除码，并在实践中证明了对于云文件系统中使用的大块大小，这些差异提高了I/O性能。几个云系统[15，10]已经采用了里德-所罗门(RS)码，因为它们具有通用性，并且能够容忍更大数量的故障。我们定义了一类新的旋转Reed-Solomon码，它比所有已知码更有效地执行降级读取，但在其他方面继承了Reed-Solomon码的可靠性和性能特性。
To reduce storage overhead, cloud file systems are transitioning from replication to erasure codes. This process has revealed new dimensions on which to evaluate the performance of different coding schemes: the amount of data used in recovery and when performing degraded reads. We present an algorithm that finds the optimal number of codeword symbols needed for recovery for any XOR-based erasure code and produces recovery schedules that use a minimum amount of data. We differentiate popular erasure codes based on this criterion and demonstrate that the differences improve I/O performance in practice for the large block sizes used in cloud file systems. Several cloud systems [15, 10] have adopted Reed-Solomon (RS) codes, because of their generality and their ability to tolerate larger numbers of failures. We define a new class of rotated Reed-Solomon codes that perform degraded reads more efficiently than all known codes, but otherwise inherit the reliability and performance properties of Reed-Solomon codes.