> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ocient.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Node Configuration with the Administrator Role

export const OcientDataIntelligencePlatform = "OcientAIQ™ Unified Data Platform";

export const Ocient = "Ocient®";

Nodes with the `admin` role have the additional responsibility to store important metadata for compression and system configuration. In most cases, an {OcientDataIntelligencePlatform} 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
</Warning>

<Info>
  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](/configure-storage-spaces).
</Info>

## 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 SQL theme={null}
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](/cluster-and-node-management#alter-node)

[Configure Storage Spaces](/configure-storage-spaces)

[Expand and Rebalance System](/expand-and-rebalance-system)