9. Rolling Restarts
When you restart multiple services, components, or hosts, use rolling restarts to distribute the task. A rolling restart stops, then starts multiple, running slave components such as DataNodes, NodeManagers, RegionServers, or Supervisors, using a batch sequence. You set rolling restart parameter values to control the number of, time between, tolerance for failures, and limits for restarts of many components across large clusters.
To run a rolling restart:
Select a Service, then link to a lists of specific components or hosts that Require Restart.
Select Restart, then choose a slave component option.
Review and set values for Rolling Restart Parameters.
Optionally, reset the flag to only restart components with changed configurations.
Choose Trigger Restart.
Use Monitor Background Operations to monitor progress of rolling restarts.
![[Important]](../common/images/admon/important.png) | Important |
|---|---|
Rolling Restarts of DataNodes is recommended to only be performed during a cluster maintenance window. |