Persistent pre-allocation and back link based write back journaling technique

Abstract

The Journaling file system keeps track of the changes in a circular log in a dedicated storage area. The file system modifications are stored as a journal transaction before writing them into the actual file system location or home location. On file system crash or system failure, the file system mounts back immediately and the awaiting journal transactions are written into the home location. Predominantly, file systems use meta-data journaling than data journaling because the latter is costly operation as it involves a double write for every data write. In our proposed persistent pre-allocation with back link technique, the file system writes are optimized and file consistency is assured. Essentially, this new technique produces write back journaling with reduced number of metadata writes with no data corruption for growing file write operations. File system modifications often create random writes, when the random writes is reduced, the SSD performance is enhanced through reduced write amplification. We implemented the proposed technique the Ext4 file system and the results on various workloads show improved write performance on the SSD block device. Also the reliability results show no data corruption after the system recovery.