• https://www.youtube.com/watch?v=OmphHSaO1sE Awesome explanation

• https://www.ibm.com/cloud/learn/etcd
  • the fault-tolerant open source key-value database that serves as the primary data backbone for Kubernetes and other distributed platforms.
• etcd is a distributed reliable key-value store for the most critical data of a distributed system, with a focus on being:
  • Simple: well-defined, user-facing API (gRPC)
  • Secure: automatic TLS with optional client cert authentication
  • Fast: benchmarked 10,000 writes/sec
  • Reliable: properly distributed using Raft

• Multiple nodes cooperate with each other through the raft consensus algorithm.
• The algorithm elects a master node as the leader, which is responsible for data synchronization and distribution.
• Quorum is a key concept in etcd. It is defined as (n+1)/2, indicating that more than half of the nodes in the cluster constitute a quorum.

Also read https://learnk8s.io/etcd-kubernetes