In this article I will briefly explain about the different components of a Nutanix cluster. The major components are listed below.
Nutanix cluster components |
- Stargate: Data I/O manager for the cluster.
- Medusa: Access interface for Cassandra.
- Cassandra: Distributed metadata store.
- Curator: Handles Map Reduce cluster management and cleanup.
- Zookeeper: Manages cluster configuration.
- Zeus: Access interface for Zookeeper.
- 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 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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