December 18, 2013
This work proposes to take methods applied successfully to model SSD cleaning algorithms in File Translation Layer (FTL) and use them to understand the behavior and performance bounds of SMR disks under realistic workloads. It aims to (a) derive algorithms which approach these bounds, (b) characterize algorithm performance in ways which allow Service Level Objectives (SLOs) to be achieved on these devices, and (c) evaluate the relative advantages of implementing SMR-aware algorithms inside the disk firmware vs. externally.The emergence of the SMR technology forces enterprise storage vendors to rapidly deploy a new HDD technology with performance characteristics very different from existing devices. Flash-based SSDs evolved via an ad-hoc process over years, with some spectacular failures along the way. The practical goal of this work is to reduce the risk of this happening with the SMR disk.