Oracle International Corporation

Oralce International Corporation

Vikram Rai

Alok Kumar Srivastava

Angelo Pruscino

Sameer Arun Joshi

Techniques are described herein for synchronizing cluster time. According to one technique, a master node is appointed in a cluster. Other 'slave' nodes periodically synchronize their clocks with the master node. To synchronize its clock with the master node, a slave node sends a timestamped message to the master node, which also timestamps the message and sends the message back to the slave node, which then timestamps the message again. Based on the timestamps, the slave node is able to determine the difference between the master node's clock's time and slave node's clock's time, compensating for the message travel time between master node and slave node. Depending on various circumstances, and based on the determined difference, the slave node adjusts its clock so that the time indicated by the slave node's clock at least begins to approach more closely the time indicated by the master node's clock.

Time synchronization in cluster systems

Synchronizing cluster time is described. Times of one or more nodes in the cluster to a master node of the cluster are synchronized. It is discovered that a node of a cluster has a clock time that is ahead of a master clock time of the master node. In response to discovering the node with the clock time ahead of the master clock time, the master node is replaced with the node ahead thereof in time, which thus becomes a new master node. The clock times of the cluster nodes are synchronized with the clock time of the new master node.

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Franklin Park, NJ, United States of America

Vikram Rai