File System Level Wear Leveling Mechanism for Non-Volatile Memory Based Storage

The access speed of STTRAM, MRAM and the other Non-volatile memory is close to that of DRAM. So they are very useful for high performance storage system and improving the performance of large computer system, but their limited write endurance is one of the most important limitations. We introduce file system level wear leveling technology for them. Using the Hash function to disperse files on the storage system, some blocks are avoided allocating repeatedly when creating and deleting files. The blocks with lower write count are chosen to avoid some blocks with centralized write operation when allocating space for file. An active heat data migration strategy is designed to reduce the I/O performance impaction of wear leveling mechanism. Finally, we implement the file system level wear leveling mechanism prototype based on the open source object-based storage device named Open-osd. Using Filebench, postmark and some trace are tested and analyzed, and the results show that the difference of write count between blocks is reduced to around one of the twentieth with original, and only reducing 6% system I/O performance and increasing about 05% amount of writing. It is verified that the file system level wear leveling mechanism is effective and stable.