Evolving Ext4 for Shingled Disks


Abutalib Aghayev, Carnegie Mellon University; Theodore Ts’o, Google, Inc.; Garth Gibson, Carnegie Mellon University; Peter Desnoyers, Northeastern University

Note: Due to technical difficulties, there is no audio of this talk.


Drive-Managed SMR (ShingledMagnetic Recording) disks offer a plug-compatible higher-capacity replacement for conventional disks. For non-sequential workloads, these disks show bimodal behavior: After a short period of high throughput they enter a continuous period of low throughput.

We introduce ext4-lazy1, a small change to the Linux ext4 file system that significantly improves the throughput in both modes. We present benchmarks on four different drive-managed SMR disks from two vendors, showing that ext4-lazy achieves 1.7-5.4x improvement over ext4 on a metadata-light file server benchmark. On metadata-heavy benchmarks it achieves 2-13x improvement over ext4 on drive-managed SMR disks as well as on conventional disks.

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@inproceedings {202248,
author = {Abutalib Aghayev and Theodore Ts{\textquoteright}o and Garth Gibson and Peter Desnoyers},
title = {Evolving Ext4 for Shingled Disks},
booktitle = {15th USENIX Conference on File and Storage Technologies (FAST 17)},
year = {2017},
isbn = {978-1-931971-36-2105},
address = {Santa Clara, CA},
pages = {105--120},
url = {https://www.usenix.org/conference/fast17/technical-sessions/presentation/aghayev},
publisher = {USENIX Association},
month = feb