There are many reasons for adding one or more nodes to an installation of Vertica:
- Increase system performance. Add additional nodes due to a high query load or load latency or increase disk space 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, e.g., less then 10 seconds, or the response time is not hardware bound.
- Make the database K-safe (K-safety=1) or increase K-safety to 2. See Failure Recovery for details.
- Swap a node for maintenance. Use a spare machine to temporarily take over the activities of an existing node that needs maintenance. The node that requires maintenance is known ahead of time so that when it is temporarily removed from service, the cluster is not vulnerable to additional node failures.
- Replace a node. Permanently add a node to remove obsolete or malfunctioning hardware.
If you install Vertica on a single node without specifying the IP address or host name (or you used
localhost), you cannot expand the cluster. You must reinstall Vertica and specify an IP address or host name that is not
Adding nodes consists of the following general tasks:
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.
Configure the hosts you want to add to the cluster.
See Before you Install Vertica in Installing 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.
- Add one or more hosts to the cluster.
Add the hosts you added to the cluster (in step 3) to the database.
You can also add nodes using the
admintoolscommand line, which allows you to preserve 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.