Abstract: In recent years,many research works have proposed new in-memory file systems to manage storage class memory (SCM),such as BPFS,PMFS and SIMFS.Since the in-memory data access is different from traditional I/O path of block-based file systems,the data consistency mechanisms are not well studied for in-memory file systems.Thus,a new consistency mechanism called direct copying was presented for in-memory file systems.The pros and cons when different consistency strategies are used in in-memory file systems were discussed.Then,different consistency mechanisms were implemented in SIMFS to test the effectiveness of the proposed methods.Finally,experiments were conducted with standard benchmark to measure the performance of different consistency mechanisms.The experimental results show that the proposed direct copying method outperforms other strategies.

Key words: Data consistency,In-memory file system,Performance optimization,Journaling file system,Virtual address space