Explain how data storage and retrieval have changed over time.

CHANGE IN DATA STORAGE AND RETRIEVAL OVER TIME

Data Storage

Data storage is a general term for archiving data in electromagnetic or other forms for use by a computer or device. Different types of data storage play different roles in a computing environment.

 

Storage Devices

A storage device is any computing hardware that is used for storing, porting and extracting data files and objects. It can hold and store information both temporarily and permanently, and can be internal or external to a computer, server or any similar computing device.

History of storage devices

Punch Cards

A punch card is a piece of stiff paper that can be used to contain digital data represented by the presence or absence of holes in predefined positions

Punch cards were the first effort at Data Storage in a machine language. Punch cards were used to communicate information to equipment “before” computers were developed. The punched holes originally represented a “sequence of instructions” for pieces of equipment, such as textile looms and player pianos.

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin, magnetisable coating on a long, narrow strip of plastic film

Magnetic tape is one of the oldest technologies for electronic data storage. While tape has largely been displaced as a primary and backup storage medium, it remains well-suited for archiving because of its high capacity, low cost and long durability

Capacity: The IBM 7340 Hyper tape drive, introduced in 1961, used a cassette with a 1 inch (2.5 cm) wide tape capable of holding 2 million six-bit characters per cassette.

Portability: One magnetic tape storage advantage is its physical lightweight and easy portability. Magnetic tapes can be easily transported to a secure, off-site location. A data vault, for example.

Speed: The standard speed for a cassette tape is 47.625 mm per second. This is half the standard speed previously used on open-reel recorders and is made possible by the improvements in tape and head quality made since the early days of tape recording.

 

Floppy disk

A floppy disk, also known as a floppy, diskette, or simply disk, is a type of disk storage composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic enclosure lined with fabric that removes dust particles.

The floppy disk drive (FDD) was invented at IBM by Alan Shugart in 1967. The first floppy drives used an 8-inch disk (later called a "diskette" as it got smaller), which evolved into the 5.25-inch disk that was used on the first IBM Personal Computer in August 1981.

Capacity: The first 8-inch floppy disk had a storage capacity of about 80 kilobytes. By 1986, IBM introduced the 3-1/2-inch floppy disk with 1.44 megabytes of storage space.

Portability: Easily portable or moveable but easily broken so portability is limited

Speed: Rotational speed is 300 RPM for the 300 Oe media and 360 RPM for the high density 600 Oe media." 3.5" Floppy Disks … Most drives rotate at 300 RPM, but some, Sony/HP in particular, rotate at 600 RPM."

 


Hard drive

A hard drive is a secondary storage device that consists of one or more platters to which data is written using a magnetic head, all inside of an air-sealed casing.

In 1956, the first hard drive to be sold commercially was invented by IBM. This hard drive, shipped with the RAMAC 305 system, was the size of two refrigerators and weighed about a ton. It held 5MB of data, at a cost of $10,000 per megabyte.

Capacity: space a hard drive or HDD holds varies in computers usually varies between 512 gigabytes and a 1 terabyte (1024) gigabyte. Most pc made in the modern day usually are built with a storage space of over 800 gigabyte.

Portability: the portability of hard drive changes depending on whether if it is an internal or external hard drive. Internal hard drives are built into the computer so portability reduces to almost nothing as the hard drive will need to be removed from the computer to be moved around. With an external hard drive, you get the same amount of space as an internal hard drive with more portability.

Speed:

An average read speed of 128 MB per second and a write speed of 120 MB per second.

In consumer products the maximum transfer rate typically ranges from about 200 MB/s to 3500 MB/s, depending on the drive.

Optical disk

An optical disk is any computer disk that uses optical storage techniques and technology to read and write data. It is a computer storage disk that stores data digitally and uses laser beams (transmitted from a laser head mounted on an optical disk drive) to read and write data. When it comes to optical disks there are three different types. These are:

a.     Compact Disk

b.    Digital Versatile Disk

c.     Blu-ray Disk

Capacity: CDs can store up to 700 megabytes (MB) of data and DVDs can store up to 8.4 GB of data. Blu-ray discs, which are the newest type of optical media, can store up to 50 GB of data.

Portability: are easily stored and portable and can usually be left in devices. Usually break easily so portability is reduced due to availability of space where they cannot be broken

Speed: CD’s have a speed of 1.229 mb/s, DVD 10.080 mb/s, Blu-ray disk 33 mb/s

Solid State Drive:

A solid-state drive is a solid-state storage device that uses integrated circuit assemblies as memory to store data persistently, typically using flash memory.

Capacity: Typically not larger than 1TB for notebook size drives; 4TB max for desktops

Portability: the portability of a SSD is similar to that of HDD. It has a version built into the computer and a portable or external version. This can be easily carried around like a mobile device.

Speed:

Thumb Drive

A thumb drive also called a USB drive or flash drive, is a small solid-state drive that connects to a device through a USB port. Because USB technology has become such a standard protocol, users can transfer files to and from most personal computers easily with these small, portable drive.

Capacity: The amount of space a thumb drive holds can be varied and the higher the space it holds the more expensive the thumb drive. The capacity of a thumb drive can vary from a mere 2 gigabytes to 512 gigabytes.

Portability: extremely portable, they are small enough to fit in a pocket or hand and can be used anywhere. One of the most used storage device in the modern world due to their low cost and high efficiency.

Speed: Adhering to the speed of a thumb drive it depnds on the type of thumbd drive being used. There are two types of thumb drive. The older version which is 2.0 and the most recnt and most used which is the 3.0 

  USB 2.0 tops out at 480 megabits per second (Mbps) / 60 megabytes per second (MBps).

  USB 3.0 goes up to 5 Gigabits per second (Gbps) / 640 MBps

 

Memory card

Capacity: the amount of space a memory card can hold is very similar to that of a thumb drive. It can vary between 2 gigabytes and go up to 128 or even 256 gigabytes.

Portability: memory cards are even more portable than thumb drives as they can be used in both mobile devices and pcs. Originally the idea of a memory card was to expand the space of only phones but after a few years’ improvements were made so that they could be used in pcs. They can be easily removed and put back or placed in another device in as easily as a few seconds.

Speed: can be from 12mb/s to 985mp/s 

Formats of data

Data format in information technology may refer to:

·        Data type- constraint placed upon the interpretation of data in a type system

·        Signal (electrical engineering)- a format for signal data used in signal processing

·        Recording format- a format for encoding data for storage on a storage medium

·        File format- a format for encoding data for storage in a computer file

o   Container format (digital), a format for encoding data for storage by means of a standardized audio/video codecs file format

·        Content format- a format for representing media content as data

o   Audio format, a format for encoded sound data

o   Video format, a format for encoded video data

Access Methods and Speeds

An access method is a software component, operating system service or network interface that handles the storage/retrieval and sending/receipt of data. Access methods provide an application programming interface (API) for programmers to perform these services, which rely on low-level, specialized instructions.

There are three different methods which can be used to access (locate) data stored on a backing storage device. They are direct access, serial access and sequential access.

Direct Access

When direct access is used the head that reads data from the storage medium can move directly to any point on the storage medium. If a particular record or file must be loaded or saved, then the head can move directly to the record/file's position on the storage medium and read the data. Records and files can therefore be located very quickly.

Magnetic disks such as hard disks and floppy disks and optical disks such as CD-ROMs use the direct access method. Direct Access is required if transaction processing is taking place.

Serial Access

When a serial access medium is being used, the head that reads data from the storage medium has limited freedom of movement. The only serial access medium is magnetic tape.

To read a particular record/file from a serial access medium, all of the data that comes before the record/file must be scanned through. The tape head cannot move to a particular record/file on the tape without reading through all of the other records that come before it.

Because of this it can take a very long time to locate a record/file on a tape and so tapes are only used for specific applications such as backup and batch processing. For these applications the speed of locating data is not important and the other advantages of magnetic tapes outweigh the slow access speed.

Sequential Access

Sequential access is a slight modification of the serial access method. This method is identical to serial access except that the records are stored on the storage medium in a particular order, e.g. by customer number. Sorting the data into an order may speed up operations such as searching the tape. The sequential access method is usually used by batch processing systems.