Aug 14, 2018

Data Storage

by Aksha Verma
Reading time: 9 mins


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Electronic data storage is the process of storing data electronically which can be done in either an analog format or a digital format on a variety of media.

The world’s technological capacity to store information electronically has grown multifold over the years. From a mere three exabytes in 1986, to 295 exabytes in 2007 and has been constantly doubling roughly every three years.

The reason for this growth of electronic data storage can be attributed to its cost effectiveness in comparison to alternative methods due to smaller physical space requirements and the ease of rewriting data on the same medium.

Data can therefore be stored electronically in the following two ways:

  1. Offline
  2. Online

1. Offline Data Storage Solution:

Offline Data Storage Solution, often labelled as the traditional form of data storage refers to the storage of data on local servers, hard drives or external storage devices.

Offline data storage is a faster mode of data storage than Internet storage as it doesn’t require upload or download of files. However, it is more susceptible to loss due to theft, natural disasters or device failure.

Offline storage solutions can be further classified into:

  • Computer storage Devices (Internal)
  • External Storage Devices

1.1 Computer Storage Devices – As computers continue to advance so do the storage space requirements. Lack of a storage device would mean that the computer will not be able to save any information and will not be able to create anything new.

The computer memory can be divided into:

1.1.1 Primary storage – Also known as main memory and is connected to the central processing unit via a memory passage. The CPU continuously reads instructions stored there and executes them as required.

The primary memory consists of:

RAM(Random Access Memory): The data stored in RAM can be accessed quickly. There are two types of RAM: DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory)

  • ROM: While the computer begins to restart, it uses ROM. It stores firmware and they contain instructions the computer can use in performing some of the most basic operations. This memory cannot be easily modified.

  • Cache: Cache is a high-speed auxillary memory that can be either used as a reserved section of main memory or a storage device.

1.1.2 Secondary storage- This memory is not directly accessible by the CPU and can only be accessed using the input/output channels. The hard disk drive is the main and largest data storage device in a computer and can store anywhere from 160 gigabytes to 2 terabytes of data. By default, most information is saved the computer hard drive.

1.2 External Storage Device - An improvement in technology over the years has led to an improvement in the capabilities of storage devices. Unlike now, early storage devices were much more expensive, larger in size, smaller in capacity, and slower than today’s storage devices.

Two main categories of storage technology used today are magnetic storage and optical storage.

1.2.1 Magnetic storage:

All magnetic storage devices are all coated with a magnetically sensitive material such as iron oxide and polarization is used to store data wherein all the ions in the magnetic material align themselves in one direction and the orientation of the magnetic field can be used to represent data. Each iron particle acts as a magnet, taking on a magnetic field when subjected to an electromagnet. The read/write heads of a disk drive contain electromagnets, which generate magnetic fields in the iron on the storage medium as the head passes over the disk. The read/write heads store a string of 1s and 0s by alternating the direction of the current in the electromagnet. To read data the process is reversed. The read/write heads pass over the disk while no current is flowing through the electromagnet. The storage medium has a charge and the electromagnet does not storage medium changes the magnet in the head which causes a small current to flow through the head in one direction or the other depending on the polarity of the field. The disk drive senses direction of flow and data is sent from the head into memory. Some type of magnetic storage devices are:

o Diskettes - The diskette drive includes a motor that rotates the disk on a spindle and the read/write heads that can move to any spot on the surface of the disk as it spins. This allows the heads to access data randomly rather than sequentially. Diskettes are most commonly used for moving files between computers not connected by a network or communication hardware, loading new programs onto a system and also to back up data or programs.

o Hard disks - Hard disk is still the most common storage device for all computers. Like diskettes hard drives store data in tracks divided into sectors. It includes one or more metal platters mounted on a central spindle, like a stack of rigid diskettes. Each platter is covered with a metal coating and the entire unit is contained in a sealed chamber. The hard disk and drive are a single unit which includes the hard disk, the motor that spins the platters and a set of read/write heads. Because you cannot remove the disk from the drive the terms hard disk and hard drive are used interchangeably. Hard drives have become the primary storage devices for PCs because they are convenient and cost effective.

o Floppy disks – It is a soft portable magnetic disk and can store data up to 1.44MB. It is slower to access than hard disks and have less storage capacity, but they are much less expensive.

o Magnetic tape - A magnetic tape is a magnetically coated strip of plastic on which data can be encoded. It is much less expensive than other storage mediums but commonly a much slower solution that is commonly used for backup.

1.2.2 Optical storage:

The most popular alternative to magnetic storage systems are optical storage media. These devices fall into the optical storage category because they store data on a reflective surface so that it can be read by a beam of laser light. A laser uses concentrated, narrow beam of light, focused and directed with lenses, prisms and mirrors. The tight focus of the laser beam is possible because all the light is of the same wavelength.

o Compact Disk Read Only Memory (CD ROM) - The CD-ROM drive for music or data reads 0s and 1s from a spinning disk by focusing a laser on the disks surface. Some areas of the disk reflect the laser light into a sensor, other areas scatter the light. A spot that reflects the laser beam is interpreted as a 1 and the absence of a reflection is interpreted as a 0. On a full CD-ROM the spiral of data stretches almost 3 miles long. A standard CD can store 650 MB of data or about 70 mins of audio.

o Digital Video Disk Read Only Memory (DVD ROM) - Digital video (or versatile) disk read only memory, is a high-density medium capable of storing a full-length movie on a single disk the size of a CD. Achieves such high storage capacities by using both sides of the disk and special data compression technologies. The latest generation of DVD-ROM use layers of data tracks; the laser beam reads data from the first layer and then looks through it to read data from the second layer. Each side of a standard DVD-ROM can hold up to 4.7 GB. Dual layer DVD-ROM can hold 17 GB of data.

o CD Recordable (CD R) - CD-R allows you to create your own CD-ROM disks that can be read by any CDROM drive. After the information has been written to the CD it cannot be changed.

o CD Rewritable (CD RW) - Using CD-RW drives the user can write and overwrite data onto CDs. With a CDRW data can be revised in the same manner as a floppy disk. One popular form of recordable CD is PhotoCD, a standard developed by Kodak for storing digitised photographic images on a CD. Many film-developing stores now have PhotoCD drives that can store your photos and put them onto a CD.

Other external storage devices also include –

1.2.3 USB Flash drive - A small, portable flash memory card that plugs into a computer’s USB port and functions as a portable hard drive. They are available in sizes such as 256MB, 512MB, 1GB, 5GB, and 16GB and are an easy way to transfer and store information.

1.2.4 Memory card - An electronic flash memory storage disk commonly used in consumer electronic devices such as digital cameras, MP3 players, mobile phones, and other small portable devices. These are usually read by connecting the device containing the card to your computer, or by using a USB card reader.

2. Online Data Storage Solution:

Online data storage, also known as Cloud storage or Hosted storage is an alternate to traditional storage mediums and refers to the process of storing digital data over the internet by accessing services provided by a third party.

With advancing times, the use of online mediums to store data is increasing tremendously as it not only prevents loss of data but also provides easy multi-platform accessibility, transfer and sharing. However, using offline modes of storage is faster than using Internet storage, because it doesn’t require one to upload or download files.

There are a large number of vendors offering online data storage services. While, some allow users to store a particular kind of data, such as photos, music or backup data, others allow multi data storage.

There are mainly three cloud-based storage models:

  • Public Cloud storage – It is best suited for unstructured data and provides a shared storage environment. Some of the top Public cloud storage service providers are Google Cloud Storage, Microsoft Azure and Amazon Glacier.
  • Private Cloud Storage – Also known as internal cloud storage is a private cloud that allows organizations to create their own dedicated environment within the firewall. Some of the top Private cloud storage service providers are Amazon Elastic Compute Cloud, IBM’s Blue cloud and Google AppEngine
  • Hybrid Cloud Storage – A cloud service that employs both private and public cloud services to perform various functions within the same organization. This allows flexibility within the organization.

Some other commonly used online data storage service providers include IDrive, Dropbox, Google Drive, ADrive and OpenDrive.


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