Database Essentials

An Exasol database runs in a cluster that contains one or more nodes. Each node is a host machine that has its own CPUs and main memory (RAM). The total number of CPUs and the total amount of RAM in a cluster determines the compute power.

A cluster can have any number of reserve nodes on standby in addition to the active data nodes. A reserve node is a node that has the same basic configuration as a data node, but which is not active and contains no data. If the nodes are set up with redundancy>1, an active node holds a mirror of the data on the neighboring node. If one of the active nodes fails, a reserve node will automatically take over the role of the failed node. Data is then copied to this node from a mirror on one of the other active nodes.

For more details about setting up redundancy in nodes, see Redundancy.

For information about how to manage clusters and nodes, see Nodes Management.

For information about the failover mechanisms in Exasol 8, see Fail Safety.