> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://ocient.ferndocs.com/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://ocient.ferndocs.com/_mcp/server.

# Node Configuration with the Administrator Role

> Understand the key design considerations for deploying Ocient, ensuring scalability and efficiency.

Nodes with the `admin` role have the additional responsibility to store important metadata for compression and system configuration. In most cases, an Ocient Hyperscale Data Warehouse™ system should have the majority of SQL Nodes assigned to the `admin` role.

## Administrator Node Redundancy

To ensure high availability and consistency, an Ocient® System must always have a minimum number of operational nodes with `admin` privileges.

Redundancy for the system configuration and dictionary compression operates using a majority present model. In a system with `N` nodes configured with the `admin` role, at least `N / 2 + 1` must be present and active for the system to function correctly, where `N` is the total number of nodes, and `N / 2` denotes the division floor (i.e., rounded down to the nearest integer).

This table shows the number of nodes with `admin` privileges that can fail before the system experiences problems. Both columns comprise only nodes assigned the `admin` role, not the entire system node count.

| **Number of Nodes** | **Node Failures Tolerated** |
| ------------------- | --------------------------- |
| 1                   | 0                           |
| 2                   | 0                           |
| 3                   | 1                           |
| 4                   | 1                           |
| 5                   | 2                           |
| 6                   | 2                           |
| 7                   | 3                           |

> **Warning**
>
> Various core system functions risk failure if the number of nodes running the `admin` role falls below the tolerance threshold. Operations that could fail include:
>
> * System startup
> * System configuration
> * Query execution
> * Data loading

> **Note**
>
> The majority present model for nodes with the `admin` role is different than parity encoding used for Foundation Nodes.
>
> For details on parity width for Foundation Nodes, see [**Configure Storage Spaces**](/guides/system-administration/configure-storage-spaces).

## Administrator Node Metadata

This table describes additional metadata files stored by nodes running the `admin` role. If you remove the `admin` role from a node, the system removes these files.

| **File path**                            | **Description**                                                     |
| ---------------------------------------- | ------------------------------------------------------------------- |
| `/var/opt/ocient/metadataStorage.raft`   | Definitions for users, network configuration, and database objects. |
| `/var/opt/ocient/globalDataStorage.raft` | Compression dictionaries for the `COMPRESSION GDC` columns.         |

## Configure Nodes with the Administrator Role

To configure a node to run the `admin` role, execute this SQL statement.

```sql
ALTER NODE nodename ADD ROLE admin;
```

It is generally a good practice to have all SQL Nodes in your system assigned to run the `admin` role. You can configure additional nodes with the `admin` role to adjust the level of redundancy to your chosen level.

## Related Links

[**ALTER NODE**](/guides/sql-reference/data-definition-language-ddl-statement-reference/cluster-and-node-management)

[**Configure Storage Spaces**](/guides/system-administration/configure-storage-spaces)

[**Expand and Rebalance System**](/guides/system-administration/maintenance-overview/expand-and-rebalance-system)