Nutanix provides two types of node and there is special hardware series as per functionality of node like compute heavy node and storage heavy node.
If you want to add a node as “Storage Node only” and don’t want to run any VM on it as per license agreement then you have to declare that node as “Never Schedulable Node” in Nutanix cluster.
Note : Never schedule-able node functionality is available in Nutanix AHV Hypervisor only.
Never Schedulable Node : Notes
There is few notes to need consider about Never Scheduable Node
- Never schedulable node will increase the data storage capacity in Nutanix cluster.
- AOS will never schedule any VM(s) to Never Schedule-able Node in any general or worst case scenarios i.e create new VM, VM migration ( Manually or automatic -ADS ), event of node failure ( VM-HA ).
- AOS feature “Never-Schedule” will ensure that Nutanix cluster will not use “Never Schedule-able Node”‘s CPU other then local CVM only for I/O handling.
- Need node License to use “Never Schedule-able Node” in Nutanix cluster.
- Nutanix advice don’t violation of your user VM licensing agreements.
- You can add any number of never-schedulable nodes to your Nutanix cluster.
- You want to change / convert the Node functionality from “Schedule-able Node” to “Never Schedule-able Node” then you have to remove that node from cluster and add back node as “Never Schedule-able Node” in Nutanix cluster.
- If you no longer need a node to work as a never-schedulable node, remove the node from the cluster.
Prerequisites to Add Never Schedule-able Node in cluster
Prerequisites before add new node as Never Schedule-able Node in the Nutanix cluster :
- There must be minimum three nodes ( Schedule-able Node) in the cluster Nutanix cluster.
- Always three working nodes ( Schedule-able or Never Schedule-able ) must in cluster to function the cluster properly.
Never Schedulable Node Configuration
After completing the prerequisites of Never Schedule-able Node Lets the to add the new node as Never Schedule-able Node in Nutanix cluster.
Step 1 : Bring that node in same subnet / VLAN network as existing Nutanix cluster in running.
Step 2 : Log in to Prism web console > Hardware > Expand cluster and lets discover node
Optional : you can discover new node through command line as well
Step 2. 1 : Log in to any Nutanix CVM in running Nutanix cluster
nutanix@cvm$ ncli cluster discover-nodes
Step 3 : Add node as Never Schedule-able Node in Nutanix cluster
nutanix@cvm$ ncli -h true cluster add-node node-uuid=uuid-of-the-node never-schedulable-node=true
Optional : Add node as Schedule-able Node in Nutanix cluster
nutanix@cvm$ ncli -h true cluster add-node node-uuid=uuid-of-the-node
How Get New node UUID ? : Follow Option 1 or 2
Option 1 : Discover new node through command
Log in to any CVM of running Nutanix cluster
nutanix@cvm$ ncli cluster discover-nodes
output
Node Position : A Node Serial : ZMxxxxxxxxxx Node Uuid : d1b9d9c3-7f6f-4cb8-bf16-f37xxxxxxxx Rackable Unit Model : NX-3xxx
Option 2 : Log in to local CVM of New Node.
Default Credential
userid : nutanix
Password : nutanix/4u
nutanix@cvm$ cat /etc/nutanix/factory_config.json
Note : Node_UUID will show in first line
If you no longer need a node to work as a never-schedulable node, remove the node from the cluster.
Conclusion
Nutanix fail-over cluster has capability to add and remove the both type of nodes in running Nutanix cluster without any interruption.
Nutanix Schedulable node or Never Schedule node give great flexibility to nutanix customer to use compute heavy node vs storage heavy node in Nutanix fail-over cluster.
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