Adding nodes

There are many reasons to add one or more nodes to a Vertica cluster:

• Increase system performance or capacity. Add nodes due to a high query load or load latency, or increase disk space in Enterprise Mode without adding storage locations to existing nodes.

  The database response time depends on factors such as type and size of the application query, database design, data size and data types stored, available computational power, and network bandwidth. Adding nodes to a database cluster does not necessarily improve the system response time for every query, especially if the response time is already short or not hardware-bound.

• Make the database K-safe (K-safety=1) or increase K-safety to 2. See Failure recovery for details.

• Swap or replace hardware. Swap out a node to perform maintenance or hardware upgrades.

Adding nodes consists of the following general tasks:

1. Back up the database.

   Vertica strongly recommends that you back up the database before you perform this significant operation because it entails creating new projections, refreshing them, and then deleting the old projections. See Backing up and restoring the database for more information.

   The process of migrating the projection design to include the additional nodes could take a while; however during this time, all user activity on the database can proceed normally, using the old projections.

2. Configure the hosts you want to add to the cluster.

   See Before you Install Vertica. You will also need to edit the hosts configuration file on all of the existing nodes in the cluster to ensure they can resolve the new host.

3. Add one or more hosts to the cluster.

4. Add the hosts you added to the cluster (in step 3) to the database.

   When you add a host to the database, it becomes a node. You can add nodes to your database using either the Administration tools or the Management Console (See Monitoring with MC). Adding nodes using admintools preserves the specific order of the nodes you add.

After you add nodes to the database, Vertica automatically distributes updated configuration files to the rest of the nodes in the cluster and starts the process of rebalancing data in the cluster. See Rebalancing data across nodes for details.

If you have previously created storage locations using CREATE LOCATION...ALL NODES, you must create those locations on the new nodes.