Restoring the Publisher Node in a Cisco Unified CM 9.1 Cluster

B.

In the given scenario, the Publisher server of a Cisco Unified CM version 9.1 cluster has suffered a catastrophic hard disk failure without Cisco Disaster Recovery System backups. The organization needs to restore the Publisher node to bring the system back to normalcy. Let's discuss each of the answer options provided and their validity:

A. Take a full DRS backup from all subscribers and reinstall the Publisher from that backup. This option is not a valid method to restore the Publisher node. DRS backup is taken for disaster recovery purposes, and it is not recommended to restore a single node from a DRS backup taken from multiple nodes. This option may result in inconsistencies and database errors.

B. Promote one of the remaining subscriber to Publisher, then install a new subscriber. This is a valid method to restore the Publisher node. In this method, one of the existing subscribers is promoted to a Publisher, and a new subscriber is installed to maintain the required number of nodes in the cluster. However, this method may cause a temporary service disruption during the failover process.

C. The Publisher node cannot be restored, but the remaining subscribers should be sufficient to support the Collaboration devices and services. This option is not valid because it suggests ignoring the failure of the Publisher node and continuing with the remaining subscribers. Although the remaining nodes can provide basic call processing functionality, the system's resilience and redundancy are severely compromised.

D. Reinstall the publisher node and restore the Publisher database from a subscriber database. This is a valid method to restore the Publisher node. In this method, the Publisher node is reinstalled, and the Publisher database is restored from a backup of one of the existing subscribers. However, this method may require additional configuration steps to ensure that the restored database is consistent with the cluster's current state.

E. Take a DRS backup from a subscriber and reinstall the Publisher from that backup. This option is not valid as it is similar to option A, which is not recommended for restoring a single node.

In conclusion, the most valid methods to restore the Publisher node in the given scenario are options B and D. The selection between the two methods depends on factors such as the severity of the service disruption and the availability of a recent backup.