1 VAS Intro

1.1 Brief Introduction

Users of paid online videos, such as online education videos, have a very high requirement against quality of service, but some types of video file storage are relatively cold which means the video content is not requested frequently. Also, the popularity of different software or game platforms is not the same.

As the disk space of CDN PoPs is limited, when the utilization rate (cache volume) reaches the configured threshold, the CDN PoPs will delete cold storage first based on certain rules, so the space will be spared for new file caching. Under the situation mentioned-above, not only the cache hit ratio will be lowered, response time prolonged, quality of service compromised, but the back-to-origin (hereafter abbreviated as BtO) requests and origin pressure will be increased, influencing user perception.

To meet the requirements of customers who have cold storage need for videos or other types of files, and who demand a high quality of service, CDNetworks has dedicated caching feature in place to enforce the caching of the specified content and to raise the caching priority. This feature increases hit ratio, improves quality of service, reduces BtO requests and also realizes other effects.

1.2 Applicable Product Lines

• Media Acceleration

1.3 Application Scenarios

This feature is applicable for all download and media services such as online education and online music, which contain relatively cold storage of paid video and require a very high level of quality of service. It can also be applied to some newly-launched services, which have a small number of resource visits and of high expectation from end users.

2 VAS Detail

2.1 Fundamentals

Dedicated caching has a higher level of priority than general caching. The higher priority guarantees that the specified content is the last to be deleted in CDN PoPs and the important or cold storage files can be obtained by end users in time, improving the quality of service for end users.

As per shown in figure 1, a certain amount of disk space in the PoPs server will be assigned to the customer who is willing to use the dedicated caching service. And the content of this customer will be preserved in this space, even though the storage is cold, without much client request. When the client makes a request for the video or other types of files in the cold storage, there is no need to go back to origin to fetch the file as it is already cached in the PoPs, so the hit ratio will be improved accordingly.

2.2 Instructions

First time use:

The following information must be provided: the domain name or URL to be enabled with dedicated caching, and the total size of files for dedicated caching (the default value is 100GB).

Modification:

The following information must be provided: the domain name or URL to be modified (which supports Regex).

3 Notice

Dedicated caching is a value-added service, and there is an extra charge for use with the charging unit being GB.