The use of solid state drives (SSDs) in data systems is increasing. Solid state drives are advantageous over hard disk drives (HDD) because SSDs have no moving parts. Thus, SSDs are not as fragile as HDDs. Further, because SSDs have no mechanical delay, SSDs are not subject to the relatively lengthy access times, seek times and latency to which HDDs are subject. For this reason, SSDs are usually much faster than HDDs. A significant drawback of SSDs, however, is their relatively high cost compared to HDDs.
SSDs can be based on either volatile (RAM-based) or non-volatile (flash) memory. Non-volatile memory can maintain information even when there is no power, whereas volatile memory requires continual power to maintain stored information. Flash memory stores information in memory cells that are made from floating-gate transistors. Solid state devices include single-level cell devices (SLC) and multi-level cell devices (MLC), for example. SLC devices store only one bit of information per cell, whereas MLC devices can store more than one bit of information per cell. Memory cells can be either NOR gate flash or NAND gate flash. NOR allows for random-access reading and NAND allows only page access.
There is a need for an improved data storage system and method that includes SSDs and utilizes data progression to improve the efficiency of the system.