On the power of asymmetry and memory in flash-based SSD garbage collection
Faculty of Sciences. Mathematics and Computer Science
Performance evaluation. - Amsterdam
, p. 1-15
University of Antwerp
The power of dd random choices has been widely recognized in the balls-and-bins, hashing and load balancing setting and various refinements such as the introduction of asymmetry or memory have been proposed. Recently, the dd-choices garbage collection algorithm for flash-based SSDs was introduced and shown to provide an excellent tradeoff between performance and simplicity. In this paper we study the impact of asymmetry and memory on the performance of the dd-choices garbage collection algorithm using both mean field models and trace-based simulations. Numerical examples demonstrate that both asymmetry and memory reduce the write amplification, however the reduction is typically less than 2% when exploiting asymmetry, while more significant gains exceeding 10% are observed when memory is introduced.