A New Multi-Tiered Solid State Disk Using Slc/Mlc Combined Flash Memory

Storing digital information, ensuring the accuracy, steady and uninterrupted access to the data are considered as fundamental challenges in enterprise-class organizations and companies. In recent years, new types of storage systems such as solid state disks (SSD) have been introduced. Unlike hard disks that have mechanical structure, SSDs are based on flash memory and thus have electronic structure. Generally a SSD consists of a number of flash memory chips, some buffers of the volatile memory type, and an embedded microprocessor, which have been interconnected by a port. This microprocessor run a small file system which called flash translation layer (FTL). This software controls and schedules buffers, data transfers and all flash memory tasks. SSDs have some advantages over hard disks such as high speed, low energy consumption, lower heat and noise, resistance against damage, and smaller size. Besides, some disadvantages such as limited endurance and high price are still challenging. In this study, the effort is to combine two common technologies - SLC and MLC chips - used in the manufacture of SSDs in a single SSD to decrease the side effects of current SSDs. The idea of using multi-layer SSD is regarded as an efficient solution in this field.