TY - GEN
T1 - An efficient and flexible metadata management layer for local file systems
AU - Liu, Yubo
AU - Li, Hongbo
AU - Lu, Yutong
AU - Chen, Zhiguang
AU - Zhao, Ming
PY - 2019/11
Y1 - 2019/11
N2 - The efficiency of metadata processing affects the file system performance significantly. There are two bottlenecks in metadata management in existing local file systems: 1) Path lookup is costly because it causes a lot of disk I/Os, which makes metadata operations inefficient. 2) Existing file systems have deep I/O stack in metadata management, resulting in additional processing overhead. To solve these two bottlenecks, we decoupled data and metadata management and proposed a metadata management layer for local file systems. First, we separated the metadata based on their locations in the namespace tree and aggregated the metadata into fixed-size metadata buckets (MDBs). This design fully utilizes the metadata locality and improves the efficiency of disk I/O in the path lookup. Second, we customized an efficient MDB storage system on the raw storage device. This design simplifies the file system I/O stack in the metadata management and allows metadata lookup to be completed with constant time complexity. Finally, this metadata management layer gives users the flexibility to choose metadata storage devices. We implemented a prototype called Otter. Our evaluation demonstrated that Otter outperforms native EXT4, XFS, Btrfs, BetrFS and TableFS in many metadata operations. For instance, Otter has 1.2 times to 9.6 times performance improvement over other tested file systems in file opening.
AB - The efficiency of metadata processing affects the file system performance significantly. There are two bottlenecks in metadata management in existing local file systems: 1) Path lookup is costly because it causes a lot of disk I/Os, which makes metadata operations inefficient. 2) Existing file systems have deep I/O stack in metadata management, resulting in additional processing overhead. To solve these two bottlenecks, we decoupled data and metadata management and proposed a metadata management layer for local file systems. First, we separated the metadata based on their locations in the namespace tree and aggregated the metadata into fixed-size metadata buckets (MDBs). This design fully utilizes the metadata locality and improves the efficiency of disk I/O in the path lookup. Second, we customized an efficient MDB storage system on the raw storage device. This design simplifies the file system I/O stack in the metadata management and allows metadata lookup to be completed with constant time complexity. Finally, this metadata management layer gives users the flexibility to choose metadata storage devices. We implemented a prototype called Otter. Our evaluation demonstrated that Otter outperforms native EXT4, XFS, Btrfs, BetrFS and TableFS in many metadata operations. For instance, Otter has 1.2 times to 9.6 times performance improvement over other tested file systems in file opening.
KW - File system
KW - Metadata
KW - Namespace
KW - Path lookup
UR - http://www.scopus.com/inward/record.url?scp=85081158149&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85081158149&partnerID=8YFLogxK
U2 - 10.1109/ICCD46524.2019.00034
DO - 10.1109/ICCD46524.2019.00034
M3 - Conference contribution
T3 - Proceedings - 2019 IEEE International Conference on Computer Design, ICCD 2019
SP - 208
EP - 216
BT - Proceedings - 2019 IEEE International Conference on Computer Design, ICCD 2019
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 37th IEEE International Conference on Computer Design, ICCD 2019
Y2 - 17 November 2019 through 20 November 2019
ER -