Telemetry Archiving: An application of non-normalised database design or How to optimise storage efficiency, retrieval speed and real-time performance.

摘要

Over the last three years, Makalumedia have developed a high performance telemetry data archive for Eutelsat. This archive initially served as data storage component of the TeleViews web application but was designed from the beginning to support a wider range of applications. It stores change-only telemetry data for all satellites (currently 25) in the Eutelsat fleet on two dedicated servers using standard PC hardware. In this paper I'll describe in detail the design of this archive, especially how we tailored the storage structure to typical use cases in accessing telemetry data; it supports extremely fast data retrieval speeds along with quasi-live streaming. The design of the archive is very scalable and it is straightforward to add new satellites or move data between servers without interrupting the availability of the archived data. The use of standard interfaces and protocols eases the integration of the archive in the distributed structures of modern control systems and organizations. Archived telemetry data is made available to other applications via a simple HTTP interface. Data is currently served in either JSON or CSV formats and extension to other formats is straightforward. The archive also supports several server-side statistical calculations, for example minimum, maximum and average, over any desired time interval and sampling period.