📄️ High Availability
A single NameNode is a single point of failure in Hadoop. Hadoop 2.x introduced NameNode High Availability (HA) using two NameNodes — an Active and a Standby — to eliminate this risk.
📄️ Security & Kerberos
By default, Hadoop runs in simple authentication mode, which offers no real security — any user can impersonate any other. For production clusters, Apache Hadoop supports Kerberos for strong mutual authentication.
📄️ HDFS Federation
The Single NameNode Bottleneck
📄️ HDFS Snapshots
What Are Snapshots?
📄️ Hadoop Configuration Tuning
Default Hadoop settings are conservative and designed for small test clusters. Production clusters require careful tuning across HDFS, MapReduce, and YARN to achieve good throughput and stability.
📄️ Rack Awareness
What Is Rack Awareness?