Next4: Snapshots in Ext4 File System

Abstract

The growing value of data as a strategic asset has given rise to the necessity of implementing reliable backup and recovery solutions in the most efficient and cost-effective manner. The data backup methods available today on linux are not effective enough, because while running, most of them block I/Os to guarantee data integrity. We propose and implement Next4 - file system based snapshot feature in Ext4 which creates an instant image of the file system, to provide incremental versions of data, enabling reliable backup and data recovery. In our design, the snapshot feature is implemented by efficiently infusing the copy-on-write strategy in the write-in-place, extent based Ext4 file system, without affecting its basic structure. Each snapshot is an incremental backup of the data within the system. What distinguishes Next4 is the way that the data is backed up, improving both space utilization as well as performance.