Rabbet: Using Layout-Aware Backup for RAID Reconstruction

Once a disk of storage system is failed, RAID mechanism will reconstruct to keep the reliability. The reconstruction leads to a sharp deterioration in I/O performance of RAID, and the storage system cannot provide high performance service for the applications. The Multi-TB disk capacity and high load of the application make the reconstruction last for a very long time. This paper proposes Rabbet, a method accelerating RAID reconstruction using data of backup. Rabbet includes a new RAID reconstruction frame, a RAID layout-aware mapping mechanism for backup, and a reconstruction algorithm. The result of experiments shows that, comparing to the classic DOR methods Rabbet shortens the RAID5 reconstruction process to 13.9%-42.8% and decreases the average response time for applications during reconstruction by 3.2%-14.6%. Rabbet also improves the reliability of storage systems.