ElasticSearch is an open source search platform that enables enterprises to implement full text search. ElasticSearch is based on Apache Lucene, an open source index and searching technology that enables almost real-time search.
Ephemeral storage is used for scratch space and as temporary storage for the operating system in a guest VM. Ephemeral storage is allocated on a per virtual instance basis and exists while the virtual instance exists. When a virtual instance is deleted, the ephemeral storage and data is deleted as well. The size of ephemeral storage is determined by the flavor of the instance. Ephemeral storage persists through reboots of the guest operating system, but is deleted when the instance is deleted.
etcd is a fully-replicated, highly available key-value distributed storage for Calico and Kubernetes. Etcd is responsible for storing and replicating data across Kubernetes and Calico clusters. Etcd relies on the Raft consensus algorithm that ensures etcd recovery from many severe hardware and software errors.