Sun Cluster HA is a hardware- and software-based high availability solution. It provides high availability support on a cluster machine and automatic data service failover in just a few seconds. It accomplishes this by adding hardware redundancy, software monitoring, and restart capabilities.
Sun Cluster provides cluster management tools for a System Administrator to configure, maintain, and troubleshoot HA installations.
The Sun Cluster configuration tolerates these single-point failures:
Server hardware failure
Disk media failure
Network interface failure
Server OS failure
When any of these failures occur, HA software fails over logical hosts onto another node and restarts data services on the logical host in the new node.
Sybase Replication Server is implemented as a data service on a logical host on the cluster machine. The HA fault monitor for Replication Server periodically probes Replication Server. If Replication Server is down or hung, the fault monitor attempts to restart Replication Server locally. If Replication Server fails again within a configurable period of time, the fault monitor fails over to the logical host so the Replication Server will be rebooted on the second node.
To Replication Server clients, it appears as though the original Replication Server has experienced a reboot. The fact that it has moved to another physical machine is transparent to the users. Replication Server is affiliated with a logical host, not the physical machine.
As a data service, the Replication Server includes a set of scripts registered with Sun Cluster as callback methods. Sun Cluster calls these methods at different stages of Failover:
FM_STOP – to shut down the fault monitor for the data service to be failed over.
STOP_NET – to shut down the data service itself.
START_NET – to start the data service on the new node.
FM_START – to start the fault monitor on the new node for the data service.
Each Replication Server is registered as a data service using the hareg command. If you have multiple Replication Servers running on the cluster, you must register each of them. Each data service has its own fault monitor as a separate process.
For detailed information about the hareg command,
see the appropriate Sun Cluster documentation.
