Storage can be defined, simply as, a device or medium which will allow you to keep your information permanently, when the computer has been switched off, so that it can be recalled and re-used again later.
The Hard Disk Drive
The electromechanical Hard Disk Drive (HDD) is a device which is usually mounted inside the computer system box. It is classified as secondary storage and is used to save permanently your program files and personal files. The actual hard disk drive consists of a set of 2 or 3 circular, spinning magnetic disks called platters, upon which data is written. Data can be written to both sides of the platter using a read/write head mounted above and below each platter. Each platter is subdivided into tracks (a series of concentric circles of data), sectors (pie shaped slices of the drive surface), TSUs (Track Sector Units – that portion of the track falling into one sector) and clusters (the smallest accessible division of data on the Hard Disk Drive). The amount of data that can be stored on a hard disk drive is determined by how close the tracks can be mounted and still read by the read/write head and by how many platters are included in the container. The whole hard disk drive is connected to the computer by a cable. This plugs into a connection on the motherboard and is powered by the Power Supply Unit (PSU).
Storage Capacity
Data storage capacity is measure in bits and Bytes. A bit is a binary digit, namely a one (1) or a zero (0). This is because the computer system, no matter how big or small it is, uses a flow of electricity to transfer data. A flow of electricity represents a one and no flow of electricity represents a zero. The computer system, therefore, works with the Binary Number System (Base 2 or Powers of Two). In comparison, humans use the Decimal Number System (Base 10 or Powers of Ten). These numbering systems can be represented as follows: BASE TEN (Decimal) And larger 105 104 103 102 101 100 BASE TWO (Binary) And larger 2 10 2 9 2 8 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2
A Byte of data is approximately one character, which is also a small amount of data.
So, we also use:
Kilo (K) ~ 1 000 times bigger than a Byte
Mega (M) ~ 1 000 000 bigger than a Byte
Tera(T) ~ 1 000 000 000 bigger than a Byte
Peta (P) ~ 1 000 000 000 000 bigger than a Byte
Exa (E) ~ 1 000 000 000 000 000 bigger than a Byte
The latest technology for the Hard Disk Drive is the Solid-State Drive (SSD). This has no moving parts like platters and read/write heads and is thus more stable and robust.