RefCRE: A Reference Count Based Rewriting Framework for VM Image Restoration

Deduplication is widely adopted in virtual machine(VM) backup to save storage space. However, the deduplication storage could cause serious fragmentation, which severely affects the performance of restoring VMs. Current studies mainly focus on backups from a single data source, whereas the backup of VM images is usually a group of behaviors. Exploiting the block reference helps to defragment deduplication storage. In this paper, we propose RefCRE, a framework for accelerating VM image restoration. The framework implements two reference count based methods (RCR and ATL) to reduce the dispersion degree of blocks and reduce the replacement frequency. Experimental results show that the framework can efficiently reduce the dispersion degree of blocks and effectively improve the restoration performance, when the cache size is properly set.