Relay all mail to an external account which can come in handy in your lab environment.
Perform HDFS audit logging.
Create Yarn nodes whitelist.
Save namespace on namenode and perform checkpoint on secondary namenode.
Inspect Hadoop configuration using command-line.
Mount HDFS as a local file system.
Create Hadoop data nodes whitelist.
The Hadoop cluster enters safe mode during the name node startup till the basic indicators are met and later in case of emergency, which means that the cluster enters read-only mode.
Keep track of network latency using SmokePing on Debian Bullseye.
Use boot parameters to limit the number of available processors.