Partitioned Real-Time NAND Flash Storage

Abstract

This paper addresses the problem of guaranteeing performance and predictability of NAND flash memory in a real-time storage system. Our approach implements a new flash translation layer scheme that exploits internal parallelism within solid state storage devices. We describe the Partitioned Real-Time Flash Translation Layer (PaRT-FTL), which splits a set of flash chips into separate read and write sets. This ensures reads and writes to separate chips proceed in parallel. However, PaRT-FTL is also able to rebuild the data for a read request from a flash chip that is busy servicing a write request or performing garbage collection. Consequently, reads are never blocked by writes or storage space reclamation. PaRT-FTL is compared to previous real-time approaches including scheduling, over-provisioning and partial garbage collection. We show that by isolating read and write requests using encoding techniques, PaRT-FTL provides better latency guarantees for real-time applications.