IIS Resource Hierarchy Failover

A failover occurs in two situations:

• The first situation occurs when the hardware or operating system experiences a major failure and the server is no longer functioning. The LifeKeeper core on the backup server detects this condition when heartbeat messages from the primary server fail. In response, the LifeKeeper core invokes the Recovery Kit’s recovery script, which brings the Internet server resources into service on the backup server.

• The second situation occurs when the Recovery Kit for IIS deep check and quick check scripts detect a failure of an IIS Site resource. These scripts return failure codes to the LifeKeeper core. The LifeKeeper core then initiates the failover process and invokes the Recovery Kit’s recovery scripts. LifeKeeper behavior at this stage depends on the configured local recovery enablement settings.
  • If local recovery is enabled, the Recovery Kit recovery scripts are invoked to attempt to restore the IIS Site resource. If the recovery attempt fails, LifeKeeper initiates the failover process.
  • If local recovery is disabled, no recovery attempt is made and the failover process begins immediately. During failover, the LifeKeeper core first stops the IIS Site resource on the failed server (if it is not already stopped), takes the associated switchable IP address and volume resources out of service, and then continues the failover to the backup server.

After the primary server is repaired, the active resource automatically returns to the primary server when the switchback type is set to Automatic. If the switchback type is set to Intelligent, a manual switchover is required.

When the IIS Site resource hierarchy on the primary server transitions out of service due to a switchover or failover, clients cannot connect to the site until the IIS Site resource hierarchy is brought into service on the backup server. Any existing client connections are disconnected during this transition.

Once the switchable IP addresses and volumes have moved to the backup server and the site is running, IIS service resumes normal operation.