Cloud object storage vendors are in the forever pursuit of better cost efficiency. The emerging Shingled Magnetic Recording (SMR) drive becomes an economically favorable choice due to significantly improved areal density. However, SMR drives were mostly deployed in the archival-class object storage because they require zone-level sequential write and erase in bulk. For standard-class object storage, previous studies and our preliminary exploration reveal that existing SMR drive solutions can suffer from severe performance penalty and unpredictability.
In this paper, we propose SMRSTORE, an SMR-based storage engine for standard-class object storage without compromising performance or durability. The key features of SMRSTORE include directly bridging the semantics of distributed file system with the zoned namespace in SMR drives, using a complete log-structured design, and applying guided data placement to reduce GC activities and achieve consistent performance. The evaluation shows that SMRSTORE delivers comparable performance as Ext4 on the Conventional Magnetic Recording (CMR) drives, and can be up to 2.16x faster than F2FS on SMR drives. Currently, we have deployed SMRSTORE in Alibaba Cloud Object Storage Service (OSS) to store hundreds of PBs of data in standard class. We plan to use SMR drives for all classes of OSS in the near future.