Cluster Time

Time among all cluster nodes in a cluster must be synchronized. Whether you synchronize the cluster nodes with any outside time source is not important to cluster operation. The Oracle Solaris Cluster software employs the Network Time Protocol (NTP) to synchronize the clocks between nodes.

In general, a change in the system clock of a fraction of a second causes no problems. However, if you run date or rdate on an active cluster, you can force a time change much larger than a fraction of a second to synchronize the system clock to the time source. This forced change might cause problems with file modification timestamps or confuse the NTP service.

When you install the Oracle Solaris Operating System on each cluster node, you have an opportunity to change the default time and date setting for the node. In general, you can accept the factory default.

When you install Oracle Solaris Cluster software using the scinstall command, the software supplies template files (see /etc/inet/ntp.conf and /etc/inet/ntp.conf.sc on an installed cluster node) that establish a peer relationship between all cluster nodes. One node is designated the “preferred” node. Nodes are identified by their private host names and time synchronization occurs across the cluster interconnect. Examples of private host names include clusternode1-priv and clusternode2-priv. For instructions on how to configure NTP, see Configuring Network Time Protocol (NTP) in Oracle Solaris Cluster Software Installation Guide.

In normal operation, you should never need to adjust the time on the cluster. However, if the time was set incorrectly when you installed the Oracle Solaris Operating System and you want to change it, the procedure for doing so is included in Chapter 9, Administering the Cluster, in Oracle Solaris Cluster System Administration Guide.