When provisioning a PostgreSQL cluster instance with an external load balancer in NDB, the administrator creates a software profile from a reference VM. The reference VM typically includes software like Patroni (for HA management), HAProxy (for internal load balancing), keepalived (for high availability IP management), and etcd (for distributed configuration). Since an external load balancer is used, the internal HAProxy can be omitted from the reference VM. NDB will rely on the external load balancer to distribute traffic, eliminating the need for HAProxy in the software profile, while the other components remain essential for cluster management.

Option A (Patroni) is incorrect because Patroni is required for PostgreSQL HA management.

Option B (HAProxy) is correct as it can be omitted when an external load balancer is configured.

Option C (keepalived) is incorrect because keepalived is needed for HA IP failover.

Option D (etcd) is incorrect because etcd is necessary for distributed configuration in the cluster.

This adjustment streamlines the profile for external load balancer use.

References

Nutanix Database Service (NDB) User Guide, Chapter 4: Managing Software Profiles, Section: Creating Software Profiles for HA Instances

Nutanix Certified Professional - Database Automation (NCP-DB) v7.5Blueprint, Section 4: Manage Database Software Profiles