# Nodes

From _Settings_ → _System_ → _Nodes,_ you can protect your server’s database from write access by activating read-only mode. This allows you to avoid modifications to your server configuration and blob stores when performing system maintenance.

To enable it:

1. Click _Nodes_, under _System_ in the _Settings_ menu
2. Click _Enable read-only_ mode

**Warning**  
Anything that would require a change to a database will fail during read-only mode.

The button becomes _Disable read-only_ mode when enabled. A banner appears above the main toolbar, notifying you that read-only mode is activated.

Disabling read-only mode, by clicking the _Disable read-only_ mode button returns the server to its original, writable state.

**Note**  
Note that if you are using one of our [High Availability deployment options](https://help.sonatype.com/en/high-availability-deployment.html "High Availability Deployment") and a node is not shut down gracefully, this node will continue to appear on the _Nodes_ page for a few seconds.

## High Availability Clustering (HA-C) (Legacy) Notes

In High Availability Clustering (Legacy) mode, the _Nodes_ screen also provides a summary of all active nodes. The screen keeps a record of all running nodes that you manage in table form.

When you click a row, you get a detailed summary of the chosen node.

The summary lists:

- _Node Identity_, a unique ID accessible via the _System Information_
- _Socket Address_, the address corresponding to the server

When running in HA-C mode the _Nodes_ screen displays all synchronized nodes in the table. View the table to monitor and verify server connections.

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