9.3.3 Host and String Failure

Figure 9-4 shows a double failure where both String 1 and phys-hahost2 fail. If the failure sequence is such that the string fails first, and later the host fails, the mediator on phys-hahost1 could be golden. In this case, we have the following conditions:

• The mediator on phys-hahost1 is golden.

• Half of the mediators are available.

• Half of the replicas are accessible.

• The mediator commit count on phys-hahost1 matches the commit count found in the replicas on String 2

Figure 9-4 Multiple Failure - One Server and One String

This type of failure is recovered automatically by Sun Cluster. If phys-hahost2 mastered the diskset, phys-hahost1 will take over mastery of the diskset. Otherwise, mastery of the diskset will be retained by phys-hahost1. After String 1 is fixed, the data on String 1 must be resynchronized with the data on String 2. For more information on the resynchronization process, refer to the Solstice DiskSuite User's Guide and the metareplace(1M) man page.

Although you can recover from this scenario, you must be sure to restore the failed components immediately since a third failure will cause the cluster to be unavailable.

If the mediator on phys-hahost1 is not golden, this case is not automatically recovered by Sun Cluster and requires administrative intervention. In this case, Sun Cluster generates an error message and the logical host is put into maintenance mode (read-only). If this or any other multiple failure occurs, contact your service provider to assist you.