NDB Architecture and Components
What the exam tests
This domain checks whether you can separate the NDB control plane from the data plane and identify which component performs each action.
Core model
- The NDB server is the control plane. It runs as a VM, stores inventory and metadata, schedules workflows, and exposes UI, CLI, and API.
- NDB agents run on managed database VMs. They execute local tasks, report health, and mediate between the server and the database engine.
- Database engines are engine-specific homes and binaries. NDB supports multiple engines; the engine version must match the software profile.
- Nutanix Prism and storage provide VM, network, snapshot, and clone primitives. NDB calls these primitives; it does not replace them.
- A Time Machine is the per-database protection object that links snapshots and logs to retention policy.
Worked example
A PostgreSQL VM is registered in NDB. During provisioning, the NDB server selects the AHV cluster and network, creates the VM, installs the agent, configures PostgreSQL, and records the database in its metadata. A later clone does not copy every block: NDB asks Nutanix storage for a snapshot-based clone, then the agent configures the clone. The control path is server to Prism and agent; the data path is storage snapshot to clone.
Traps
Do not describe the NDB server as hosting the database files; it orchestrates. Do not assume the agent is optional after registration; lifecycle jobs depend on it. Do not confuse a Prism snapshot with an NDB Time Machine snapshot; NDB adds policy, metadata, and log context. Do not place the NDB server in a network that cannot reach agents and Prism.