File size growth is driven by many factors, including broadband penetration, larger inexpensive storage devices, and high-definition video. Many companies are now finding it feasible to deliver full DVD images (4-5 GB) over the public Internet. As HD-DVD and Blu-Ray formats become popular, it is inevitable that file sizes will grow to 50 GB or more.
There are a number of challenges inherent in delivering large files. First, the average time to download a large file can be significant and many applications may not download all data sequentially. In some cases, applications may actually download the last part of a file before the first part. Therefore, when only a small amount of a file is requested, or a user pauses a download, it can result in the download either failing or being delayed until after the entire file has been retrieved.
The second is the “fat file paradox” – why does data traveling at the speed of light often take such a long time to make it across the country? With the proliferation of large files on the Internet, users are finding that latency between user and the file ultimately dictates throughput or the speed at which users can view content. In addition, network congestion and capacity problems further impact throughput, and these problems, coupled with the greater distance between server and end user, create additional opportunities for packet loss to occur, further reducing quality. The reduction in quality caused by limited throughput and increased packet loss may manifest itself in the delivery of a video encoded at a lower bit rate, or in a significantly increased wait time for a file download to complete.
Finally, many large files are rarely watched in their entirety. Therefore, it is helpful to many software and media delivery companies to store only the portion of a file that is requested by end users in the Akamai network. This way, only the requested portions will be efficiently distributed to the farthest reaches of the Internet.
Media Downloads: If an end user requests the download of a 60-minute movie, for example, but only watches the first 10 minutes, Akamai’s Large File Download Optimization allows Akamai to only cache the part of the file the user wants to watch and not have to cache the entire movie.
Software Downloads: An end user might start to download a large 5 GB software file, then pause halfway through the download, and resume 30 minutes later. Upon resuming the download, Akamai’s Large File Download Optimization allows the Akamai network to only request the part of the file that has not yet been downloaded, rather than transferring the entire file again. This significantly speeds up the experience for the end user.
Find this article at: http://www.labnol.org/internet/pressrelease/full-dvd-movies-software-image-downloads-over-the-web/1272/
