Design and Evaluation of a New Approach to RAID-0 Scaling
Design and Evaluation of a New Approach to RAID-0 Scaling
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DOI：
10.1145/2491054
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发表时间：
2013-11
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通讯作者：
Guangyan Zhang;Weimin Zheng;Keqin Li
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作者：
Guangyan Zhang;Weimin Zheng;Keqin Li
通过添加磁盘来扩展RAID-0卷可以同时增加其存储容量和I/O带宽。为了保留循环数据分布，现有的扩展方法需要迁移所有数据。如此大规模的数据迁移会导致长时间的重新分配，并对应用程序性能产生负面影响。在本文中，我们将介绍一种称为FastScale的RAID-0扩展新方法。首先，FastScale最大限度地减少了数据迁移，同时保持了统一的数据分布。它只从旧磁盘移动足够的数据块，以填充新磁盘的适当部分。其次，FastScale通过访问聚合和惰性检查点优化数据迁移。访问聚合使数据迁移具有更大的吞吐量，因为磁盘寻道减少。惰性检查点可在不影响数据一致性的情况下最大限度地减少元数据写入次数。使用几个真实的系统磁盘跟踪，我们评估的性能FastScale通过比较与SLAS，现有的最有效的缩放方法之一。实验结果表明，FastScale可以在较小的应用I/O开销的情况下，将重分配时间减少86.06%。实验还表明，使用FastScale扩展的RAID-0的性能几乎相同，甚至优于循环RAID-0。
Scaling up a RAID-0 volume with added disks can increase its storage capacity and I/O bandwidth simultaneously. For preserving a round-robin data distribution, existing scaling approaches require all the data to be migrated. Such large data migration results in a long redistribution time as well as a negative impact on application performance. In this article, we present a new approach to RAID-0 scaling called FastScale. First, FastScale minimizes data migration, while maintaining a uniform data distribution. It moves only enough data blocks from old disks to fill an appropriate fraction of new disks. Second, FastScale optimizes data migration with access aggregation and lazy checkpoint. Access aggregation enables data migration to have a larger throughput due to a decrement of disk seeks. Lazy checkpoint minimizes the number of metadata writes without compromising data consistency. Using several real system disk traces, we evaluate the performance of FastScale through comparison with SLAS, one of the most efficient existing scaling approaches. The experiments show that FastScale can reduce redistribution time by up to 86.06% with smaller application I/O latencies. The experiments also illustrate that the performance of RAID-0 scaled using FastScale is almost identical to, or even better than, that of the round-robin RAID-0.