What are storage space, bandwidth and data transfer?

It is very common to use bandwidth and data transfer synonymously, but the two words have distinctive meanings. The bandwidth refers to data tranfer rate, while the data transfer denotes amount of data transferred. Although they are different, the two words are interchangeably used in the web hosting industry.

Bandwidth is defined as amount of data transmitted over unit time. In other words, bandwidth is how fast data flows on a given transmission path or medium. The bandwidth of T1 transmission media is 1.54 Mbps (Mega bits per second), and OC-3 is approximately 155 Mbps. If a given facility has higher bandwidth, the website will load faster because it can transfer more data per second.

Data transfer refers to amount of traffic generated and transported from one location to another. From web hosting perspective, the data transfer refers to amount of data that is transferred to and from your website either by you uploading files, your visitors viewing and downloading files, and emails transported from the server to your computer. Data transfer is measured in bytes (B), kilo bytes (1 thousand bytes or KB), mega bytes (1 million bytes or MB) giga bytes (1 billion bytes or GB) or tera bytes (1 trillion bytes or TB). If you upload 1MB file, and your visitors download the file 999 times, you've just transferred 1,000 MB or 1GB of data.

Depending on what type and size of information you provide to your visitors and how many visitors you expect your website, your data transfer requirement will greatly change. If you provide mostly static text, your data transfer requirement will be relatively small. On the other hand, if you offer multimedia files such as MP3, WAV, AVI and MPG files, your data transfer requirement will be a lot higher. Multiply the data you'll be providing to your yours by number of visitors you expect on a given month, and you'll have a rough idea of required data transfer amount.

To give you numeric examples, think of a site offering static text. If a website delivers 10,000 pages per day with average page size of 20 KB, the data transfer per month will be 6GB (30 days x 10K pages x 20 KBytes). Average website receives about 50 visitors per day, and uses less than 300 MB of data tranfer.

Even though the cost of bandwidth has been reduced significantly over the last several years, providing higher bandwidth will cost more money to web hosts. To provide more bandwidth to the users, it will generally require more server resources to provide such services. Any host offering unlimited data transfer at any price will not likely be in business if their users do use them. The limiting factor is the server resources which prevents a user from using unlimited bandwidth. The bottomline is there is no such thing as unlimited data transfer.

This article is written by Scott Seong, President and CEO of Edula, Inc. If you have questions or comments about this article, please forward them to feedback@edula.com.