Fault-Aware Prediction-Guided Page Offlining for Uncorrectable Memory Error Prevention

Uncorrectable memory errors are the major causes of hardware failures in datacenters leading to server crashes. Page offlining is an error-prevention mechanism implemented in modern operating systems. Traditional offlining policies are based on correctable error (CE) rate of a page in a past period. However, CEs are just the observations while the underlying causes are memory circuit faults. A certain fault such as a row fault can impact quite a few pages. Meanwhile, not all faults are equally prone to uncorrectable errors (UEs). In this paper, we propose a fault-aware prediction-guide policy for page offlining. In the proposed policy, we first identify row faults based on CE observations as the preliminary candidates for offlining. Leveraging the knowledge of the error correction code, we design a predictor based on error-bit patterns to predict whether a row fault is prone to UEs or not. Pages impacted by the UE-prone rows are then offlined. Empirical evaluation using the error log from a modern large-scale cluster in ByteDance demonstrates that the proposed policy avoids several times more UEs than the traditional policy does at a comparable cost of memory capacity loss due to page offlining.