Data storage devices may generally be divided into word-addressed storage devices and block-addressed storage devices. In a word-addressed storage device, the smallest addressable data unit is a single data word. In a block-addressed storage device, the smallest addressable data unit is a data block, which may include a sequence of multiple data words. In general, a data word may refer to a standard smallest unit of processed data in a data access system. In some examples, a data word may be a single bit, 8 bits (i.e., a byte), 16 bits, 32 bits, or 64 bits. In additional examples, the data word may correspond to the width of a data bus connected to or within the data access system.
One example of a block-addressed storage device is a hard disk drive. The data blocks in a hard drive are often referred to as sectors, which typically contain 512 bytes. In many hard drives today, the individual sectors within a hard drive are indexed according to a logical block addressing scheme. Under such a scheme, each sector within the hard drive is mapped to a unique logical block address (LBA). The entire collection of LBAs associated with a hard drive may be referred to as an LBA space. Typically, the LBA space starts with an LBA equal to zero and increments by one for each subsequent LBA.
Another example of a block-addressed storage device is a block-addressed solid-state storage device. The data blocks in such devices may be referred to as pages. Thus, the smallest addressable data unit from which data can be read and to which data can be written is usually a page. Example page sizes for block-addressed solid-state storage devices include page sizes of 2 kilobytes (KB), 4 KB and 8 KB.
Unlike hard drives, solid state storage devices typically do not require mechanically-moving parts in order to transfer data into and out of the storage device. For example, a solid-state storage device may store data by changing the state of electrical components within the device. Because of seek times and rotational latency associated with the moving parts within a hard drive, hard drives generally require a greater amount of time to perform access operations as compared to solid-state storage devices. Thus, there is increasing interest in using solid state storage devices to emulate the functionality of a hard drive.