Achieving precise coordinated cluster time in a cluster environment

Abstract

A time-keeping mechanism is proposed for providing microsecond-level consistent time across a cluster of computers. The proposed mechanism is based on a new clock steering algorithm that uses piecewise linear mapping to align a local clock to an external reference clock in a smooth manner. We present two realizations of the algorithm: one is based on pulse-per-second (PPS) and the other is based on low-latency timing message exchange. The time derived by the proposed mechanism is called CCT (coordinated cluster time). It has a well-defined interface such that it can be used by applications with little overhead. Moreover, the interface deals completely with leap second issues. We implemented CCT on IBM BladeCenters and compared it to NTP. Experimental results demonstrate that the proposed mechanism achieves one microsecond precision.