OpsCenter 4.0 User Guide

Node management operations

You can run operations (or actions) on nodes in an easy to use, visual way, that takes the guess work out of the proper way to do things.

Managing nodes en masse

Most node management operations can be run on multiple nodes of your choosing (for example, all the nodes in a cluster, all the nodes in a single datacenter, or a handful of problem nodes. The operations run in a rolling fashion and do not continue on to the next node until the previous one has completed successfully. If the operation fails on a node, the entire process stops.

To run an operation on multiple nodes, select those nodes in List View and choose the appropriate action.

Notifications appear when the operation starts and completes.

Managing single nodes

To run an operation on a single node, click that node from Ring View or List View and choose the action you want to run from the Actions dropdown:.

Operations details

View Metrics (single node only)
Redirects you to the Performance area of OpsCenter where you can select metrics graphs and configure performance views for the selected node.
View Replication (ring view, single datacenter only)
Shows the replication relationships between the selected node and other nodes in the cluster, based on the selected keyspace.
Configure (single node only)
Modify settings specified in cassandra.yaml for the selected node.
When the configuration is saved, an option will be presented to restart the DSE or Cassandra process in order for the changes to take effect.
Start/Stop
Starts or stops the DSE or Cassandra process on the node.
Restart
Restarts the DSE or Cassandra process on the node. If running on multiple nodes, each node is started as soon as the start command for the previous node returns. If you want the operation to wait for thrift to be active on each node before continuing, use the Rolling Restart action.
Cleanup
Removes rows which the node is no longer responsible for. This is usually done after changing the partitioner tokens or the replication options for a cluster.
Compact
Performs a major compaction, which is not a recommended procedure in most Cassandra clusters.
Flush
Causes the recent writes currently stored in memory (memtables) to be flushed to disk as persistent SSTables.
Repair
Makes a node consistent with its replicas by doing an in-memory comparison of all the rows of a column family and resolving any discrepancies between replicas by updating outdated rows with the current data.
Perform GC
Forces the Java Virtual Machine (JVM) on the selected node to perform a garbage collection (GC).
Decommission (single node only)
Removes a node from the cluster and streams its data to neighboring replicas.
Drain (single node only)
Causes the recent writes currently stored in memory (memtables) to be flushed to disk as persistent SSTables and then makes the node read-only. The node stops accepting new writes. This is usually done when upgrading a node.
Move (single node only)
Changes the partitioner token assignment for the node, thus changing the range of data that the node is responsible for. Not enabled if vnodes are enabled.
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