VSD: A Framework of Stackable Virtual Snapshot Device

On demand of various applications for storage virtualization, this paper presents a stackable block-level virtual snapshot device (VSD) based on the virtual storage pool. With the strategy of stackable block device, VSD employs a read-only snapshot model with serial connection, and a tree model mixed with serial and parallel connection for writable snapshot. Moreover, two data updating schemes, Copy on Write and Realloc on Write, are integrated into VSD. Thus, VSD supports various applications such as data backup and recovery, data version management and volume clone and so on. Finally, the storage requirements and I/O performance of VSD are evaluated.