An Adaptive, Low-Cost Wear-Leveling Algorithm for Multichannel Solid-State Disks

作者：Chang Li Pin^*; Chou Tung Yang; Huang Li Chun

来源：ACM Transactions on Embedded Computing Systems, 2013, 13(3): 55.

DOI：10.1145/2539036.2539051

• Design
• Performance
• Algorithm
• Flash memory
• wear leveling
• solid-state disks

Multilevel flash memory cells double or even triple storage density, producing affordable solid-state disks for end users. As flash memory endures only limited program-erase cycles, solid-state disks employ wear-leveling methods to prevent any portions of flash memory from being retired prematurely. Modern solid-state disks must consider wear evenness at both block and channel levels. This study first presents a block-level wear-leveling method whose design has two new ideas. First, the proposed method reuses the intelligence available in flash-translation layers so it does not require any new data structures. Second, it adaptively tunes the threshold of block-level wear leveling according to the runtime write pattern. This study further introduces a new channel-level wear-leveling strategy, because block-level wear leveling is confined to a channel, but realistic workloads do not evenly write all channels. The proposed method swaps logical blocks among channels for achieving an eventually-even state of channel lifetimes. A series of trace-driven simulations show that our wear-leveling method outperforms existing approaches in terms of wear evenness and overhead reduction.

• 出版日期2013-12