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

TTFLASH is a \"tiny-tail\" flash drive (SSD) that eliminates GC-induced tail latencies by circumventing GC-blocked 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 capacitor-backed 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.