Wear Unleveling under Unbalanced Page Endurance in NAND Flash

25 Jun 2015

Wear Unleveling: Improving NAND Flash Lifetime by Balancing Page Endurance on FAST 2014.

bit_error_rate

The start point of this paper is the observation that the various pages that constitute a block deteriorate at significantly different speeds. This paper use relief cycle to address this problem.

We define a relief cycle on a page the fact of not programming it between two erase cycles.

Two Relief Plan studied:

  1. The reactive approach use the correlation between a page position in a block and its endurance and relieve the weakest pages from the very first writes to the device.
  2. The proactive technique detect the weak pages on the go.

relief_plan

Results shows that the proactive technique is more efficient than the reactive one.