Efficient Learning on High-dimensional Operational Data

In networked systems engineering, operational data gathered from sensors or logs can be used to build data-driven functions for performance prediction, anomaly detection, and other operational tasks. The number of data sources used for this purpose determines the dimensionality of the feature space for learning and can reach millions for medium-sized systems. Learning on a space with high dimensionality generally incurs high communication and computational costs for the learning process. In this work, we apply and compare a range of methods, including, feature selection, Principle Component Analysis (PCA), and autoencoders with the objective to reduce the dimensionality of the feature space while maintaining the prediction accuracy when compared with learning on the full space. We conduct the study using traces gathered from a testbed at KTH that runs a video-on-demand service and a key-value store under dynamic load. Our results suggest the feasibility of reducing the dimensionality of the feature space of operational data significantly, by one to two orders of magnitude in our scenarios, while maintaining prediction accuracy. The findings confirm the Manifold Hypothesis in machine learning, which states that real-world data sets tend to occupy a small subspace of the full feature space. In addition, we investigate the tradeoff between prediction accuracy and prediction overhead, which is crucial for applying the results to operational systems.