Reliability Evaluation

Some reliability tests was performed to determine the time each component can work without crash or service problems. Tests show that push server and database server are the most reliable components of the system. In one case, those servers was tested to run four weeks on medium load. Those servers never crashed in other tests as well. So the average time of continuous service of the database server and push server is estimated to be as long as several months.

The client is much less reliable. The interface between the client core and the MpegTV player is quite complicated and the source code for MpegTV is not available, so the additional work is required to trouble-shut it. In average, the client can work several hours without problems, what is in most cases sufficient for positive interactive experience.

The average time to work for the acquisition server is 20-40 hours. The problem is the Mpegator capture board driver, which works at the kernel level. One of the most important problems of Windows NT is the fact that Microsoft provides third-party vendors with SDK to develop hardware drivers at the kernel level. Those drivers are closed-sourced and usually are not evaluated by the Microsoft. At the other hand, third-party vendors usually do not have NT kernel sources as well. So the fact that the driver for the capturing board works at the kernel level without protection makes the whole system very unstable. During the development of the acquisition server, Windows NT used to crash up to 10 times per day. With the last version of acquisition server the system works much more stable, but even now its reliability may not be considered as acceptable.