An Effective Hierarchical PRAM-SLC-MLC Hybrid Solid State Disk

Currently, SLC-MLC hybrid SSD (solid state disk) products become mature. Phase-change random access memory (PRAM) is one of the new non-volatile memory materials used to enhance the limitation of original SLC-MLC hybrid SSD. Through reorganizing the basic functional modes among SLC, MLC, and PRAM, we proposed a new hybrid SSD architecture named PRAM-SLC-MLC Hybrid SSD (PH-SSD), in which a hierarchical updating method is designed. The PH-SSD employs PRAM as a primary updating area, uses SLC as a secondary updating area, uses MLC for main data storage, and performs data migration via a small capacity DRAM. Based on this proper arrangement, the PH-SSD can improve write performance and lifetime of SSD significantly. Through simulation, the PH-SSD achieves over 240% speedup and prolongs the lifetime by up to 2-3 times compared with the previous architecture.