Abstract:Given that non-logical volume block devices under the Linux operating system need to create temporary snapshots without additional block devices being added to store data, this study designs and implements a snapshot system for Linux non-logical volume block devices. The system has an application layer and a generic block layer of the inner nuclear layer and is based on copy-on-write (COW). The application layer analyzes the user’s creation or deletion commands and transmits them to the generic block layer. The general block layer creates or deletes the snapshot devices and intercepts the general block layer I/O (bio) request of the source device and performs COW after the snapshot is created. Experimental results show that the system can create snapshots correctly. The optimal copy block size is 4 MB. The minimum impact on the write performance of the source device is less than 10%.