Logical Volume High Performance Snapshot Based on Out-of-Band Storage Virtualization

Snapshot implemented at logical volume level adapts to different underlayer physic storage devices, and transparently provides data protection service for many kinds of upper layer applications. A scalable metadata managing strategy is proposed, and with this strategy, storage system can freely support more than one type of snapshot volume to meet different requirements of applications. By compacting snapshot index data and constructing composite snapshot volume list with Finesnap volume and Checkpoint volume, storage system maintains high performance and high resource utilization ratio while the time to recovery from snapshot volume being short. After adopting self-adaptive snapshot generation policy, modification to data block will be traced, and the time interval of generating a new snapshot volume can be dynamically shifted to follow the waving of application loads. The snapshot system LVHPsnap built on the above technologies performs good performance in representative experiments. For example, when the ratio of Finesnap volume to Checkpoint volume is 4 to 1 and 8 to 1, the performance of LVHPsnap rises by 109.45% and 130.45% as the performance of cluster virtualization system LVM2, and the used space of LVHPsnap is only 43.40% and 31.35% of LVM2.