NobLSM: an LSM-tree with non-blocking writes for SSDs

Solid-state drives (SSDs) are gaining popularity. Meanwhile, key-value stores built on log-structured merge-tree (LSM-tree) are widely deployed for data management. LSM-tree frequently calls syncs to persist newly-generated files for crash consistency. The blocking syncs are costly for performance. We revisit the necessity of syncs for LSM-tree. We find that Ext4 journaling embraces asynchronous commits to implicitly persist files. Hence, we design NobLSM that makes LSM-tree and Ext4 cooperate to substitute most syncs with non-blocking asynchronous commits, without losing consistency. Experiments show that NobLSM significantly outperforms state-of-the-art LSM-trees with higher throughput on an ordinary SSD.