Saturday, June 30, 2018

Introduction to Nutanix cluster components

In this article I will briefly explain about the different components of a Nutanix cluster. The major components are listed below.

Nutanix cluster components
  1. Stargate: Data I/O manager for the cluster.
  2. Medusa: Access interface for Cassandra.
  3. Cassandra: Distributed metadata store.
  4. Curator: Handles Map Reduce cluster management and cleanup.
  5. Zookeeper: Manages cluster configuration.
  6. Zeus: Access interface for Zookeeper.
  7. Prism: Management interface for Nutanix UI, nCLI and APIs.
Stargate
  • Responsible for all data management and I/O operations.
  • It is the main point of contact for a Nutanix cluster.
  • Workflow: Read/ write from VM < > Hypervisor < > Stargate.
  • Stargate works closely with Curator to ensure data is protected and optimized.
  • It also depends on Medusa to gather metadata and Zeus to gather cluster configuration data.
Medusa
  • Medusa is the Nutanix abstraction layer that sits infront of DB that holds the cluster metadata.
  • Stargate and Curator communicates to Cassandra through Medusa.
Cassandra
  • It is a distributed high performance and scalable DB.
  • It stores all metadata about all VMs stored in a Nutanix datastore.
  • It needs verification of atleast one other Cassandra node to commit its operations.
  • Cassandra depends on Zeus for cluster configuration.
Curator
  • Curator constantly access the environment and is responsible for managing and distributing data throughout the cluster.
  • It does disk balancing and information life cycle management.
  • It is elected by a Curator master node who manages the task and job delegation.
  • Master node coordinates periodic scans of the metadata DB and identifies cleanup and optimization tasks tat Stargate or other components should perform.
  • It is also responsible for analyzing the metadata, this is shared across all Curator nodes using a Map Reduce algorithm. 
Zookeeper
  • It runs on 3 nodes in the cluster.
  • It can be increased to 5 nodes of the cluster.
  • Zookeeper coordinates and distributes services.
  • One is elected as leader.
  • All Zookeeper nodes can process reads.
  • Leader is responsible for cluster configuration write requests and forwards to its peers.
  • If leader fails to respond, a new leader is elected.
Zeus
  • Zeus is the Nutanix library interface which all other components use to access cluster configuration information.
  • It is responsible for cluster configuration and leadership logs.
  • If Zeus goes down, all goes down!
Prism
  • Prism is the central entity of viewing  activity inside the cluster.
  • It is the management gateway for administrators to configure and monitor a Nutanix cluster.
  • It also elects a node.
  • Prism depends on data stored in Zookeeper and Cassandra.

Note: All the info provided above are based on Nutanix 4.5 Platform Professional (NPP) administration course.

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