Fault Groups
Fault groups let you configure Vertica for your physical cluster layout. Sharing your cluster topology allows you to use Terrace Routing to reduce the buffer requirements of large queries and helps minimize the risk of correlated failures inherent in your environment, usually caused by shared resources.
In versions of Vertica prior to 9.3.0, fault groups were used in Eon Mode to define subclusters. From 9.3.0 and onwards, subclusters are now defined separately. See Subclusters for more information.
Fault groups now only have an effect in Enterprise Mode databases.
Vertica automatically creates fault groups around control nodes (servers that run spread) in large cluster arrangements, placing nodes that share a control node in the same fault group. Automatic and user-defined fault groups do not include ephemeral nodes because such nodes hold no data.
Consider defining your own fault groups specific to your cluster's physical layout if you want to:
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Use terrace routing to reduce the buffer requirements of large queries.
- Reduce the risk of correlated failures. For example, by defining your rack layout, Vertica could tolerate a rack failure.
- Influence the placement of control nodes in the cluster.
Vertica supports complex, hierarchical fault groups of different shapes and sizes. The database platform provides a fault group script (DDL generator), SQL statements, system tables, and other monitoring tools.
See High Availability with Fault Groups for an overview of fault groups with a cluster topology example.