Improving internal parallelism of solid state drives with selective multi-plane operation

Solid state drives (SSDs) achieve a significantly better performance than hard disks by internally implementing channel level, chip level, and die level parallelism. However, the plane level parallelism has not been sufficiently exploited, because of the constraint that the target pages of the planes must be in the same location. To overcome this constraint, a policy that enforces the multi-plane operation by matching the position of the target pages while wasting clean pages is proposed. However, this policy excessively increases the number of block erasures, which leads to reducing the stability and lifetime of the SSD. To solve this problem, this Letter proposes a policy that determines whether to perform the multi-plane operation considering the number of wasted clean pages. The performance evaluation using representative server workloads shows that the proposed policy improves an average performance by up to 28.82% over the policy that does not perform the multi-plane operation, without significantly increasing the number of block erasures.