Availability-Aware Cache Management with Improved RAID Reconstruction Performance

The RAID reconstruction performance has a significant impact on the availability of RAID-structured storage systems due to the high disk failure rate. Most existing cache managements for RAID-structured storage systems focus on improving the performance or the energy efficiency, while they do not intent to improve the RAID availability by boosting the RAID reconstruction process. In this paper, we propose a novel and practical Availability-aware Cache Management to make the reconstruction process more sequential in the physical disks and reduce the extra reconstruction I/O requests. We implement a prototype of Availability-aware Cache Management, called Shaper, to verify its effectiveness on the RAID reconstruction. Shaper does not affect the I/O performance in the normal mode, but has potential to significantly reduce the RAID reconstruction time and the average user response time during reconstruction simultaneously.