Tiny-Tail Flash: Near-Perfect Elimination of Garbage Collection Tail Latencies in NAND SSDs


Shiqin Yan, Huaicheng Li, Mingzhe Hao, and Michael Hao Tong, University of Chicago; Swaminathan Sundararaman, Parallel Machines; Andrew A. Chien and Haryadi S. Gunawi, University of Chicago


TTFLASH is a “tiny-tail” flash drive (SSD) that eliminates GC-induced tail latencies by circumventing GCblocked I/Os with four novel strategies: plane-blocking GC, rotating GC, GC-tolerant read, and GC-tolerant flush. It is built on three SSD internal advancements: powerful controllers, parity-based RAIN, and capacitorbacked RAM, but is dependent on the use of intra-plane copyback operations. We show that TTFLASH comes significantly close to a “no-GC” scenario. Specifically, between 99–99.99th percentiles, TTFLASH is only 1.0 to 2.6× slower than the no-GC case, while a base approach suffers from 5–138× GC-induced slowdowns.

Open Access Media

USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.

@inproceedings {202247,
author = {Shiqin Yan and Huaicheng Li and Mingzhe Hao and Michael Hao Tong and Swaminathan Sundararaman and Andrew A. Chien and Haryadi S. Gunawi},
title = {Tiny-Tail Flash: Near-Perfect Elimination of Garbage Collection Tail Latencies in {NAND} SSDs},
booktitle = {15th {USENIX} Conference on File and Storage Technologies ({FAST} 17)},
year = {2017},
isbn = {978-1-931971-36-2},
address = {Santa Clara, CA},
pages = {15--28},
url = {https://www.usenix.org/conference/fast17/technical-sessions/presentation/yan},
publisher = {{USENIX} Association},

Presentation Audio