There are three main categories of storage devices: optical, magnetic and semiconductor.
The earliest of these was the magnetic device. Computer systems began with magnetic storage in the form of tapes (yes, just like a cassette or video tape). These graduated to the hard disk drive and then to a floppy disk. All magnetic media use the same general process of a read/write head magnetizing material. On a hard drive, the materials are magnetized on a glass or aluminum disk. Early storage was small. It would take many tapes to back up a mainframe system - a large system with few programs and many users - and many floppies were needed to back up significant work on a personal computer because of the low storage capacity. In the stone age of personal computers, all programs, and the work accomplished using them, were stored on 5 1/4-inch floppy disks. The storage capacity of that floppy was typically only for text and was 360 kilobytes (KB).
Magnetic media transitions were made to larger capacity portable disks such as the ZIP drive. These started with 100 MB sizes and moved to 250 and 500 MB. Part of the trouble with the ZIP drive was the speed with which they developed - it was so fast that the manufacturer neglected to keep backward compatibility going. In other words, the drive hardware for the 250-MB ZIP wouldn't work for the 100 MB disk, and the 250 disk couldn't be used in the 100. We've moved light years beyond that to improved internally-mounted hard drives, which can hold at least a terabyte of information. Think of a terabyte as enough different music to listen to while working a full-time job for an entire year! And these same hard drives have become portable and lightweight enough to carry around with us, giving us the ability to bring software and data files everywhere we go. The original magnetic media became cumbersome. Not all machines had ZIP drives installed, and frequently, a document or database large in size took up several floppies.
2.Optical Storage
About that time, optical devices were starting to be marketed. An optical storage device is written and read with a laser. It is strong and can handle temperature fluctuations much better than magnetic media. Because the floppy was so inexpensive at this time, it took several years before the optical drives became affordable to the general and small business consumer.
The disks used for storage (like CDs, DVDs and Blu-rays) were more expensive than floppies but held a lot of data. A compact disc (CD) can hold 700 MB of data, or roughly a little over an hour of music. It actually took until CD players became common in homes and cars for the playing of music for CDs to come down in price enough for more use by consumers. Digital video discs (DVDs) began being issued for consumer-released movies. A single-sided DVD holds 4.7 gigabytes (GB) of data, so a normal, not overly-computerized two-hour movie will fit.
3.Semiconductor
Semiconductor memory is an electronic data storage device, often used as computer memory, implemented on a semiconductor-based integrated circuit. There are many different types of implementations using various technologies.
Most types of semiconductor memory have the property of random access which means that it takes the same amount of time to access any memory location, so data can be efficiently accessed in any random order. This contrasts with data storage media such as hard disks and CDs which read and write data consecutively and therefore the data can only be accessed in the same sequence it was written.
Semiconductor memory also has much faster access times than other types of data storage; a byte of data can be written to or read from semiconductor memory within a few nanoseconds, while access time for rotating storage such as hard disks is in the range of milliseconds. For these reasons it is used for main computer memory (primary storage), to hold data the computer is currently working on, among other uses.
Although semiconductor storage devices are usually used for RAM, there are also some secondary storage device that utilise the semiconductor technology.For example , NVRAM (Flash memory). It is often used as a semiconductor version of a hard disk, to store files. It is used in portable devices such as PDAs, USB flash drives, and removable memory cards used in digital cameras and cellphones.
4. Cloud Storage
Cloud storage is a model of data storage in which the digital data is stored in logical pools, the physical storage spans multiple servers (and often locations), and the physical environment is typically owned and managed by a hosting company. These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment protected and running. People and organizations buy or lease storage capacity from the providers to store user, organization, or application data.
Thats all for this post.
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