# Process counts, node roles and external services

*Tableau Architect Study Guide · Design a Tableau Infrastructure · Last updated November 13, 2026 · https://www.certifyforce.com/study-guide/tableau-architect/design-a-tableau-infrastructure/process-counts-node-roles-and-external-services*

Size a Tableau Server topology: how process counts are set and what a Backgrounder instance buys, how node count drives the Coordination Service ensemble, which Backgrounder node roles isolate which jobs, how to retire a File Store node, which colocations shorten backups, and when an external repository or External File Store fits.

- Certification: Salesforce Tableau Architect
- Exam section: Design a Tableau Infrastructure
- Study guide: https://www.certifyforce.com/study-guide/tableau-architect

**Official exam objective:**

> 1.4 Design an appropriate process topology: 1.4.1 Specify process counts (sizing); 1.4.2 Specify node count; 1.4.3 Specify service-to-node relationships (node roles), including service isolation and service colocation; 1.4.4 Specify when to use external services.

## What the exam expects

- Specify process counts with `tsm topology set-process` and size Backgrounder capacity from what one instance can run.
- Specify node count and the matching Coordination Service ensemble size and failure tolerance.
- Specify service-to-node relationships: Backgrounder node roles for isolation, File Store retirement, and colocations that shorten backups.
- Decide when an external repository or External File Store fits, and what responsibility it moves to your team.

Key terms:
- **Backgrounder**: the process that runs extract refreshes, subscriptions, flows and other server jobs.
- **Node role**: a node-level setting that limits which Backgrounder jobs, or which extract queries, a node prefers.
- **Coordination Service ensemble**: the 1, 3 or 5 Coordination Service instances that keep a quorum on topology, configuration and state.
- **External services**: the repository on external PostgreSQL, or File Store on a network share, both requiring Advanced Management.

## Key facts

| Fact | Detail | Source |
|---|---|---|
| set-process scope | One process and one node per command | [tsm topology](https://help.tableau.com/current/server/en-us/cli_topology_tsm.htm) |
| Backgrounder concurrency | One job at a time per instance | [Backgrounder Process](https://help.tableau.com/current/server/en-us/server_process_backgrounder.htm) |
| Backgrounder ceiling | Pages disagree: half the cores, or half to all cores on a separate node | [Backgrounder Process](https://help.tableau.com/current/server/en-us/server_process_backgrounder.htm), [Optimize for Extracts](https://help.tableau.com/current/server/en-us/perf_optimize_extracts.htm) |
| Ensemble sizes | 1, 3 or 5; maximum 5 | [Coordination Service Ensemble](https://help.tableau.com/current/server/en-us/distrib_ha_zk.htm) |
| Five-member ensemble | Tolerates two member failures | [Coordination Service Ensemble](https://help.tableau.com/current/server/en-us/distrib_ha_zk.htm) |
| Roles per node | One; all Backgrounder nodes together cover all jobs | [Node Roles](https://help.tableau.com/current/server/en-us/server_node_roles.htm) |
| no-flows | All jobs except flows | [Node Roles](https://help.tableau.com/current/server/en-us/server_node_roles.htm) |
| Node-role change | Requires a restart | [Node Roles](https://help.tableau.com/current/server/en-us/server_node_roles.htm) |
| File Store decommission | Read-only, no unique content left | [tsm topology](https://help.tableau.com/current/server/en-us/cli_topology_tsm.htm) |
| Backup colocation | File Store with Administration Controller helps most | [Backup and Restore](https://help.tableau.com/current/server/en-us/db.htm) |
| External repository HA | Not set up or managed by Tableau Server | [External Repository](https://help.tableau.com/current/server/en-us/server_external_repo.htm) |
| 2024.2 external PostgreSQL | 15.6 minimum through 2024.2.8 | [External Repository](https://help.tableau.com/current/server/en-us/server_external_repo.htm) |
| External File Store access | Data Engine reads extracts over the network | [External File Store](https://help.tableau.com/current/server/en-us/server_external_filestore_storage.htm) |

## Check yourself

- How many Coordination Service instances does Tableau recommend for a four-node cluster?
- Why place the Coordination Service on nodes running few other services?
- When is `--override` needed with `tsm topology filestore decommission`?
- Why do jobs from a crashed Backgrounder usually still run?

## Sources

- [tsm topology](https://help.tableau.com/current/server/en-us/cli_topology_tsm.htm)
- [Tableau Server Backgrounder Process](https://help.tableau.com/current/server/en-us/server_process_backgrounder.htm)
- [Optimize for Extracts](https://help.tableau.com/current/server/en-us/perf_optimize_extracts.htm)
- [Recommended Baseline Configurations](https://help.tableau.com/current/server/en-us/server_baseline_config.htm)
- [Workload Management through Node Roles](https://help.tableau.com/current/server/en-us/server_node_roles.htm)
- [Deploy a Coordination Service Ensemble](https://help.tableau.com/current/server/en-us/distrib_ha_zk.htm)
- [Tableau Server Processes](https://help.tableau.com/current/server/en-us/processes.htm)
- [Tableau Server External Repository](https://help.tableau.com/current/server/en-us/server_external_repo.htm)
- [Tableau Server External File Store](https://help.tableau.com/current/server/en-us/server_external_filestore_storage.htm)
- [Backup and Restore](https://help.tableau.com/current/server/en-us/db.htm)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 10 linked practice questions, and unlimited timed mock exams are included with the Tableau Architect pack (USD $19): https://www.certifyforce.com/practice-exams