In a high-availability (HA) Tableau Server setup, theRepository(PostgreSQL) has an active and passive instance. Failover occurs if the active Repository fails. Let's dive into the process:
* HA Setup:
* Two Repository instances across nodes (active/passive).
* Failover switches to the passive instance if the active one becomes unavailable (e.g., crash, network issue).
* Cluster Controller:
* Role: Monitors all processes (e.g., Repository, File Store) across nodes, detecting failures via heartbeats and status checks.
* Failover Decision: If the active Repository stops responding, Cluster Controller initiates failover, promoting the passive instance to active.
* Coordination: Works with Coordination Service (ZooKeeper) to update topology but makes the initial detection call.
* Option A (Cluster Controller): Correct.
* Why: It's the watchdog process, constantly monitoring Repository health and triggering failover when needed.
* Option B (Coordination Service): Incorrect.
* Role: ZooKeeper maintains cluster state and coordinates topology updates post-failover, but doesn't detect the failure-Cluster Controller does.
* Option C (Gateway): Incorrect.
* Role: Routes client requests-unrelated to internal process monitoring or failover.
* Option D (Backgrounder): Incorrect.
* Role: Executes background tasks-no involvement in Repository failover decisions.
Why This Matters: Understanding failover ensures HA reliability-Cluster Controller is the linchpin for resilience.