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.

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@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},
month = feb

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