Hybrid SSD with PCM

Solid-State Drive, popularly known as SSD is now widely used in computer system and industry. This is a new type of memory which is smaller and lighter as compared to HDD. During a “clean” shutdown, most host systems, initiate a command (the STANDBY IMMEDIATE command) to an SSD to give the SSD enough time to prepare for the shutdown. This allows the SSD to save data currently in transition (in temporary buffers) to the non-volatile NAND media. However, during an unsafe power shutdown, the SSD abruptly loses power before the host system can initiate the STANDBY IMMEDIATE command. This prevents data in the temporary buffers from being saved in the non-volatile NAND. In this paper, we advance two new hybrid SSD architectures which are composed of PCM and NAND Flash. In these architectures, data loss during unplanned power shutdown can be avoided.