Reconsidering Single Failure Recovery in Clustered File Systems
How to improve the performance of single failure recovery has been an active research topic because of its prevalence in large scale storage systems. We argue that when erasure coding is deployed in a cluster file system (CFS) existing single failure recovery designs are limited in different aspects: neglecting the bandwidth diversity property in a CFS architecture, targeting specific erasure code constructions, and no special treatment on load balancing during recovery. In this paper, we reconsider the single failure recovery problem in a CFS setting, and propose CAR, a cross rack aware recovery algorithm. For each stripe, CAR finds a recovery solution that retrieves data from the minimum number of racks. It also reduces the amount of cross rack repair traffic by performing intra rack data aggregation prior to cross rack transmission. Furthermore, by considering multi stripe recovery, CAR balances the amount of cross rack repair traffic across multiple racks. Evaluation results show that CAR can effectively reduce the amount of cross rack repair traffic and the resulting recovery time.
2016 46th Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN)