Removing Nodes From a Database

As long as there are enough nodes remaining to satisfy the K-Safety requirements, you can remove the node from a database. You cannot drop nodes that are critical for K-safety. See Lowering K-Safety to Enable Node Removal

You can remove nodes from a database using one of the following methods:

• The Management Console interface
• The Administration Tools interface

Prerequisites

Before attempting to remove a node from the database, ensure the following prerequisites are met:

• Your database must be running.
• You must back up the database.
• If necessary, lower the K-safety of your database if the cluster will not be large enough to support its current level of K-safety after you remove nodes. Remember you must have enough nodes to satisfy K-Safety requirements.

Remove Hosts From the Database with Management Console

Remove nodes with Management Console from the Manage page. You can only remove nodes that belong to the database cluster. You cannot remove DOWN nodes.

Remove database nodes as follows:

1. Select the node you want to remove.
2. Click Remove node in the Node List.

When you remove a node the state changes to STANDBY. You can add STANDBY nodes back to the database later, see Using the Management Console to Replace Nodes.

Remove Hosts From the Database with Administration Tools

To remove unused hosts from the database using Administration Tools:

1. Open the Administration Tools. See Using the Administration Tools for information about accessing the Administration Tools.
2. On the Main Menu, select View Database Cluster State to verify that the database is running. If the database is not running, start it.
3. From the Main Menu, select Advanced Menu and select OK.
4. In the Advanced menu, select Cluster Management and select OK.
5. In the Cluster Management menu, select Remove Host(s) from Database and select OK.
6. When warned that you must redesign your database and create projections that exclude the hosts you are going to drop, select Yes.

7. Select the database from which you want to remove the hosts and select OK.

   A list of currently active hosts appears.

8. Select the hosts you want to remove from the database and select OK.
9. When prompted, select OK to confirm that you want to remove the hosts.
10. When informed that the hosts were successfully removed, select OK.

11. If you removed a host from a Large Cluster configuration, open a vsql session and run the following command:

    SELECT realign_control_nodes();

    For more details, see REALIGN_CONTROL_NODES.

12. If this host is not used by any other database in the cluster, you can remove the host from the cluster. See Removing Hosts From a Cluster.