Modernizing File System through In-Storage Indexing


Jinhyung Koo, Junsu Im, Jooyoung Song, and Juhyung Park, DGIST; Eunji Lee, Soongsil University; Bryan S. Kim, Syracuse University; Sungjin Lee, DGIST


We argue that a key-value interface between a file system and an SSD is superior to the legacy block interface by presenting KEVIN. KEVIN combines a fast, lightweight, and POSIX compliant file system with a key-value storage device that performs in-storage indexing. We implement a variant of a log-structured merge tree in the storage device that not only indexes file objects, but also supports transactions and manages physical storage space. As a result, the design of a file system with respect to space management and crash consistency is simplified, requiring only 10.8K LOC for full functionality. We demonstrate that KEVIN reduces the amount of I/O traffic between the host and the device, and remains particularly robust as the system ages and the data become fragmented. Our approach outperforms existing file systems on a block SSD by a wide margin – 6.2× on average – for metadata-intensive benchmarks. For realistic workloads, KEVIN improves throughput by 68% on average.

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@inproceedings {273719,
author = {Jinhyung Koo and Junsu Im and Jooyoung Song and Juhyung Park and Eunji Lee and Bryan S. Kim and Sungjin Lee},
title = {Modernizing File System through In-Storage Indexing},
booktitle = {15th {USENIX} Symposium on Operating Systems Design and Implementation ({OSDI} 21)},
year = {2021},
isbn = {978-1-939133-22-9},
pages = {75--92},
url = {},
publisher = {{USENIX} Association},
month = jul,