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Why do not all SolidFire nodes have a role?

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Applies to

NetApp Element software

Answer

An odd number of nodes always maintains a quorum. In a four-node cluster, there will be three ensemble nodes. There will be five ensemble nodes in a cluster with five or more nodes. This allows for a simple two-thirds or three-fifths majority to exist.

Additional Information

  • Ensemble nodes in the cluster handle Quorum calculation, configuration management, and other tasks. Quorum is always maintained by an odd number of nodes. In a four node cluster, there will be 3 ensemble nodes. In a cluster with five or more nodes, there will be 5 ensemble nodes. This allows for a simple two-thirds or three-fifths majority to exist
  • The Cluster Master node performs cluster-wide administrative tasks and contains the Management Network Virtual IP address (MVIP) and the Storage Network Virtual IP address (SVIP)
  • Users cannot typically modify or define which nodes assume any roles. Not every node in a cluster will have a role, only the Cluster Master and either 3 or 5 Ensemble nodes, and these roles can and do often overlap

To determine which nodes of your cluster are acting in what role you can:

  • Log in to the Element UI by opening a browser and going to https://<MVIP>/ 
    • Once logged in, navigate to the nodes list under Cluster > Nodes
    • Look for the column labeled Node Role
  • Log in to Active IQ, select the cluster you wish to view and click on Nodes in the left hand menu
    • Look to the far right and you should see a column labeled Role
  • Use the GetClusterInfo API as described in the Element API Reference Guide
    • In the output displayed, look for "mvipNodeID": to determine which node is the acting Cluster Master
    • Also listed in the output will be "ensemble": followed by a list of IP addresses of the nodes acting as Ensemble members
      • The IPs are the Cluster IP (Bond10G) addresses of the nodes
    • This API can be run from Postman, by making a HTTPS POST request or by using the API Collection found in Active IQ

For additional information, please refer to the Product Documentation

 

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