PARALLEL DATA LAB 

PDL Abstract

Evolving Ext4 for Shingled Disks

15th USENIX Conference on File and Storage Technologies (FAST '17), Feb 27–Mar 2, 2017. Santa Clara, CA.

Abutalib Aghayev, Theodore Ts’o*, Garth A. Gibson, Peter Desnoyers^

Carnegie Mellon University
* Google, Inc.
^ Northeastern University

http://www.pdl.cmu.edu/

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-lazy, 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.

FULL PAPER: pdf