Being Accurate Is Not Enough: New Metrics for Disk Failure Prediction

Traditionally, disk failure prediction accuracy is used to evaluate disk failure prediction model. However, accuracy may not reflect their practical usage (protecting against failures, rather than only predicting failures) in cloud storage systems. In this paper, we propose two new metrics for disk failure prediction models: migration rate, which measures how much at-risk data is protected as a result of correct failure predictions, and mismigration rate, which measures how much data is migrated needlessly as a result of false failure predictions. To demonstrate their effectiveness, we compare disk failure prediction methods: (a) a classification tree (CT) model vs. a state-of-the-art recurrent neural network (RNN) model, and (b) a proposed residual life prediction model based on gradient boosted regression trees (GBRTs) vs. RNN. While prediction accuracy experiments favor the RNN model, migration rate experiments can favor the CT and GBRT models (depending on transfer rates). We conclude that prediction accuracy can be a misleading metric. Moreover, the proposed GBRT model offers a practical improvement in disk failure prediction in real-world data centers.