Wednesday, September 18, 2013

Digital Storage

Google data center
Data is very important in today's world. There is data about everything. There is data about how much food you eat stored somewhere. Data about how you spend your weekend stored somewhere. Now you are probably wondering. Well there is this thing called Facebook and other social networks where you kind of update your daily activity. All this data including pictures and videos have to be stored somewhere. Big companies like Google have large data centers which store this information and make it available to you via the internet. I am however not not going to discuss large scale data storage. I will be talking about personal data storage.

Magnetic Tape 

Magnetic tape was invented for recording sound in 1928 in Germany, It is still used in some data centers for data backups as it is cheaper for large scale backup. Tape can store up to 8.5 TB of data. Modern tapes are packaged in  cassettes and cartridges and are of varying sizes and capacities depending on the type and length.

Floppy disks

floppy disc
Floppy disks or diskettes were also very famous storage devices in the early days of computing. They utilize a thin and flexible magnetic material to store data. These devices were also available in various sizes most notably the 3 1/2 floppy disk. This disk had a capacity ranging from 360KB to 1.44MB.
NB: For those who were born yesterday, this is the reason why your Save icon looks like that.

Magnetic Disks

Mechanical Hard drive
The best example of a magnetic disk is a Hard drive (HDD). A hard disk is made of multiple magnetic disks. These are magnetized surfaces that can store large quantities of data and can easily be read from and written onto.

3.5-inch Hard drives in desktop computers and 2.5-inch in laptops are the two most common form factors for modern hard drives . Hard drives are connected to the computer by standard interface cables such as SATA (Serial ATA), USB or SAS (Serial attached SCSI) cables.

Mechanical hard drives have are capable of more storage space but are slower than Solid state drives when it comes to data transfer.

So how do they work?

Data, which is always just a bunch of zeros and ones to a computer is represented by north magnetic pole and south magnetic pole to represent  the 0s and 1s. This makes reading easy by detecting the magnetic poles and determining whether its a 0 or 1.

The Optical Disk

CD/ DVD/ Blu-ray
Optical Disks include CD (Compact Disc), DVD, (Digital Versatile Disc), HD DVD and Blu-ray disc.
Standard CDs have a diameter of 120 millimeters  and can hold up to 80 minutes of uncompressed audio or 700 MB of data.

So how do CDs work

A CD is written onto by using an intense laser beam to burn pits or ditches into its body. These pits are the data. When reading from a CD, a less intense semiconductor laser is focussed through the bottom of the poly-carbonate (plastic) layer. The laser reflects deifferently as it touches the shiny CD surface as it either hits the pit of the smooth surface.
As the CD is spinning and the laser is scanning, every change from a  pit to flat surface and vice versa indicates a one, while no change indicates a series of zeros. Remember computers only read zeros and ones.

Flash memory

Flash memory is Electronic non-volatile computer storage. For the geeks, it's based on NAND logic gates. Non-volatile means that it can retain the data even when the power source has been turned off. This is the opposite of RAM (Random Access Memory) which is volatile and therefore loses all its content when power is turned off.

Flash memory is becoming the most used storage option as it is getting cheaper, requires less power to run as there are no moving mechanical parts and is able to be implemented in almost all sizes.
Examples of flash memory include Flash disks/ Thumb drives/ Pen drives. SD cards which by the way stands for Secure Digital. SD cards are available in various sizes but most common are the standard SD card as used in Digital Cameras and Micro SD as used in smartphones.

Solid State Hard drive.
Flash memory is used for the internal storage in most portable electronics and is becoming popular in Hard drives as well. SSD (Solid State Drives) are flash based computer Hard drives. These drives are faster and use less power. However they are relatively more expensive than magnetic Hard drives and do not have the storage capacity that conventional ones have.
This will however change very soon