Computer data storage is the component of the PC which holds digital information for a particular period of time. Data storing is one of the most important functions of a PC. Along with CPU and Input and Output devices, it is considered as core component of a PC.

Formats of stored data

Data is stored in the storage device using binary format. Audio, pictures, text, numerals and any other information are converted into a sequence of bits or binary digits. Binary digits could hold the value of either 0 or 1 only. The set of 8 consecutive bits is called a byte. Byte is the most common unit of storage.

Storage Hierarchy

Based on the bandwidth,latency and cost per bit, the memory types are organized into storage hierarchy. The band width of the memory types at the higher positions of the storage hierarchy is more than of the memory types that at the lower positions. Also, if the position is higher, then the latency is also less. There are 4 type in the hierarchy namely primary, secondary, tertiary and off-line storage.

Primary Storage

CPU could directly access memory type of primary storage. Random Access Memory or RAM is an example of this type of memory. Though RAM is tiny sized and light, but it is quite expensive. It is also volatile. RAM does not retain information, when not powered up. Two more types of primary storage are Processor Register and Processor Cache. CPU contains the processor registers. The size of the register could be 1 byte, 2 bytes, 4 bytes or even 8 bytes. CPU performs various operations on the registers. Among all forms of storage, registers are the fastest to access. Processor Cache is slower than registers but faster than main memory. It is used to improve the performance of the PC . Most widely used information store in the main memory is copied into processor cache. This makes the information access time much lesser.

Secondary Storage

CPU cannot directly access memory type of secondary storage. The CPU uses its input and output channels to access secondary storage data. It is non volatile which means it does not lose data while not powered up. Hard disk drives, optical storage drives,flash memory,floppy drives are some examples of secondary storage category. This is the most important storage for PC because information is stored in it permanently. If by any reason the stored data gets corrupted , the computer support becomes essential to restore the corrupt data.

Tertiary storage

Tertiary storage involves robotic mechanism which inserts and takes out removable mass storage media into storage device as per system requirements. It is mainly used for accessing the huge amount of old and rarely accesses data. Optical jukeboxes and tape libraries are two examples of tertiary storage.

Off-line storage

Off-line storage devices are not under the control of any processing unit. While storing or retrieving information offline storage devices are connected to the CPU. Once the data transfer is done, the device is removed from the processor. These types of devices are used mainly for data transfer.

Recovering lost data

Data stored in the storage devices could be lost,damaged or corrupted due to many reasons such as hardware failure, human error,software crash etc. Remote support could come handy in retrieving lost,damaged or corrupted data.