Updated: October 4, 2007
Applies To: Windows Server 2008, Windows Server 2008 R2
When streaming digital media content, fault tolerance refers to the ability of a streaming media system to maintain, or at least recover, service after a system fault. The likelihood of a fault in the system resulting in failure is also a measure of the fault tolerance of the system. Fault tolerance can also be measured in terms of the availability of the system or the percentage of up-time for the system.
A streaming media system is nothing more than a chain of components stretching from the content origin to the consumer. Like a chain, each component must adequately perform its assigned task or the system itself fails.
Faults can occur anywhere in a streaming media system. Upstream faults, in relation to Windows Media Services, are those that have to do with the source of the content, such as an encoder or digital media library. Downstream faults are those having to do with distribution of the content to the client, such as faults in distribution servers or cache/proxy servers.
The key to fault tolerance in a streaming media system is redundancy. A system that relies on a single component at any stage in the media distribution process is vulnerable to failure.