Data Storage Types
Data storage, also commonly known as memory or storage is one of the most crucial tasks performed by computers. All devices that are used to store data make use of diverse technologies and store data or information for a specific period of time. Information is stored in computer data storage devices in digital forms. Data storage types are usually categorized on the basis of the tasks they perform. The hierarchy of data storage is as follows:
Primary storage is also referred to as internal memory or main memory and is the only storage that is accessible to the CPU directly. It is basically the memory storage part of the computer system. Primary storage is inclusive of the Random Access Memory (RAM) and the Read Only Memory (ROM).
- Random Access Memory (RAM): RAMs are usually light, smaller in size and quite expensive as well. It is used by the computer for temporary storage of information, more like a scratch pad. This particular primary storage type is volatile and loses all the information stored when the computer is turned off. However, the access rate – the time required to access the memory – of RAM is often greater than the memory of ROM. As mentioned earlier, RAMs are quite expensive than ROMs.
- Read Only Memory (ROM): Read only memory storage type is used for permanent storage of information and is a non-volatile storage technology. The data stored in this memory is either during the manufacturing of the system itself or later by the computer user. As this type of memory is non-volatile, the data once stored cannot be altered. Also, ROMs are less expensive than RAMs.
Secondary storage is also referred to as auxiliary storage or external memory. This storage type differs from the primary storage in a way that it is not accessible by the CPU directly. Magnetic tapes, hard disks and all other external storage devices make a part of the secondary storage. This storage type is external to the processor and is usually used to augment the storage capacity of the computer. The secondary storage can retain information or memory even after the computer is turned off and hence is non-volatile. Some of the most commonly used secondary storage devices include the following:
- Hard Disks: Generally known as a disk drive or hard drive, this type of secondary data storage stores and offers substantially faster access to large amounts of information or data. The information is stored on surfaces that are electromagnetically charged and are called platters. Hard disks now come as an entirely sealed unit within the CPU. Portable hard disks are also available in the market.
- DVD: Also known as Digital Video Disc or Digital Versatile Disc, a DVD is an optical disc of high density with large capacity for storing pictures, data and sound. The data storage capacity of a single layer, single sided DVD disc is 4.7 GB, which is about seven times larger than the storage capacity of a compact disc.
- Blu-ray Discs: These secondary data storage devices are also referred to as BD. Blu-ray discs are often used for high-definition video storage and also by gamers. In terms of physical dimensions, these discs are similar to CDs and DVDs. The only difference between these storage devices is that the storage capacity of blu-ray discs is much larger when compared to that of CDs and DVDs. These are also optical storage devices.
- Compact Discs: Compact discs (CDs) are generally used to store information for a longer period of time. These carry out optical storage of information and are non-volatile. Compact discs are of two types: CD-Recordable (CD-R) and CD-Rewritable (CD-W). CD-R discs are write-once media, whereas CD-W is rewritable and the data can be erased and re-recorded any number of time.
Tertiary storage, also known as tertiary memory, offers a third level of data storage. This storage type is inclusive of devices that are connected to the computer as removable mass data storage devices. Tertiary storage devices are commonly used for the storage of files that are rarely accessed by the user. The main benefit of the tertiary level of data storage is to provide huge capacity for storage at low costs. These storage devices comprise of fixed storage drives as well as removable media units. The former category is fixed to the computer system and the latter can be removed from the drives in order to expand the data storage capacity with more media units.
In addition to the above mentioned types of data storage methods, the most recent and popularly used method is cloud storage. This is an enterprise-level data storage type and is used by business organizations for the storage of valuable business data.