RAID-6Plus: A Fast and Reliable Coding Scheme Aided by Multi-failure Degradation
RAID-6Plus: A Fast and Reliable Coding Scheme Aided by Multi-failure Degradation
复制标题
DOI：
10.1007/978-3-319-26979-5_15
复制
发表时间：
2015-12
期刊：
影响因子：
--
通讯作者：
Mingzhu Deng;Yang Ou;Nong Xiao;Songping Yu;Wei Chen;Zhiguang Chen;Fang Liu
中科院分区：
文献类型：
--
作者：
Mingzhu Deng;Yang Ou;Nong Xiao;Songping Yu;Wei Chen;Zhiguang Chen;Fang Liu
现有的三重容错码假定故障是独立的和瞬时的。这种假设忽略了多失效发生的潜在机制，也忽略了重建窗口的影响。这些代码不适应实际应用中的故障发生模式。因此，第三个奇偶校验驱动器几乎处于空闲状态，因为它设置为仅在无人值守的较低级别故障情况下处理三重故障情况。此外，随着磁盘容量的增加，单次故障重建的问题也会恶化，系统的可靠性会随着用户体验的降低而降低。针对这些问题，本研究提出了一种在RAID-6基础上扩展的快速可重构编码方案。RAID-6Plus通过重新编码第三个奇偶校验驱动器来保持较小的重建窗口。现有代码通过完全组合为三重故障提供绝对可靠性。与之形成对比的是，RAID-6Plus采用了短组合，能够在重建过程中极大地重复使用重叠的元素，以重新制作第三个奇偶校验驱动器。较短的组合缩短了单次故障的重建窗口，避免了重建窗口中的多故障重叠。多故障降级的能力为RAID-6Plus提供了(1)与RTP和STAR相比更好的系统性能和(2)与RAID-6相比增强的可靠性。
Existing triple-failure-tolerant codes assume that failures are independent and instantaneous. Such assumptions overlook the underlying mechanism of multi-failure occurrences and ignored the effect of reconstruction window. These codes are not adapted to the occurrence pattern of failure in real-world applications. As a result, the third parity drive is almost idle as it set to handle the triple-failure scenario only with lower-level failure situations unattended. Furthermore, the problem of single failure rebuild deteriorates with the increasing disk capacity, and the system’s reliability will decrease with user experience impaired. Aiming at these problems, a fast reconstructable coding scheme extended from RAID-6 has been developed in this study. RAID-6Plus maintains a smaller reconstruction window by recoding the third parity drive. Existing codes provide absolute reliability for triple failures via full combinations. As a contrast, RAID-6Plus employs short combinations which are able to greatly reuse overlapped elements during reconstruction to remake the third parity drive. The short combinations shorten the reconstruction window of single failure, which avoids multi-failure overlapping in the reconstruction window. The capability of multi-failure degradation provides RAID-6Plus with (1) a better system performance comparing to RTP and STAR and (2) an enhanced reliability comparing to RAID-6.