ESnapII: A Writable Dependent Snapshot System with Shared Cache

Snapshot technology, which has been widely used in data storage system for data protections and other tasks such as data mining and data cloning, is becoming one of the key technologies in storage area. ESnap improved the performance, resource consumption and reliability compared with traditional LVM snapshot implementation. But it still has some problems: (i) high memory consumptions caused by snapshot metadata, (ii) not support writable snapshot. A novel optimization of Esnap called ESnapII, which alleviates all the above four difficulties is proposed in this paper. In detail, a global metadata cache shared by all snapshots belongs to the same VG is proposed to reduce the memory consumption; Future more, a writing mechanism is presented for both dependent and independent snapshot. Experiment results show that ESnapII has higher performance and lower resource utilization rate than previous work.