Database Reference
In-Depth Information
Cassandra fault tolerance
Well, one of the prime reasons for using Cassandra as a data store is its fault-tolerant cap-
abilities. It's not driven by a typical master-slave architecture, where failure of the master
becomes a single point of system breakdown. Instead, it harbors a concept of operating in a
ring mode so that there is no single point of failure. Whenever required, we can restart the
nodes without the dread of bringing the whole cluster down; there are various situations
where this capability comes in handy.
There are situations where we need to restart Cassandra, but Cassandra's ring architecture
equips the administrator to do this seamlessly with zero downtime for the cluster. This
means that in situations such as the following that requires a Cassandra cluster to be restar-
ted, a Cassandra administrator can restart the nodes one by one instead of bringing down
the entire cluster and then starting it:
• Starting the Cassandra daemon with changes in the memory configuration
• Enabling JMX on an already running Cassandra cluster
• Sometimes machines have routine maintenance and need restarts
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