Arbiter connected (optional)

[TDW1]

I deployed a host node to a new cluster in the federation.  It shows alive and connected  when I run svt-federation-show, but right after connected it says optional.  What does this mean?

[Mahesh202]

Hi TDW1

The "optional" state in the output of the svt-federation-show command means that the host node has been added to the federation, but it is not currently hosting any virtual machines.

When a host node is added to a SimpliVity federation, it goes through a process of "discovery", during which the node's resources are scanned and added to the federation. Once the discovery process is complete, the node is marked as "alive" and "connected" in the federation, but it may not yet be fully utilized.

If the node is not currently hosting any virtual machines, it will be marked as "optional" in the output of svt-federation-show. This simply means that the node is available to host virtual machines if needed, but it is not currently being used for that purpose.

If you later create virtual machines on this node, it will be automatically marked as "required" in the federation, indicating that it is now being used to host virtual machines.

Hope this helps!!

Regards
Mahesh.

[rakesh_93]

@TDW1 
Hi it means that The cluster does not require Arbiter software, but Arbiter software is configured and connected.
For example, a single node cluster or a 3-node cluster does not require an arbiter. It is mandatory for a 2-node cluster and would not show 'optional' in that case.

[Mahesh202]

Hi TDW1

Yes, that's correct. In a SimpliVity Federation, an arbiter is used to prevent a "split-brain" scenario in which both nodes in a two-node cluster believe they are the primary node, leading to data inconsistencies and potential data loss.

In a single-node cluster or a three-node cluster, there is no need for an arbiter, so if an arbiter is configured and connected, it may show as "optional" in the output of the svt-federation-show command. However, in a two-node cluster, an arbiter is required, so it would not show as "optional".

Hope this helps.!!

Regards
Mahesh.

[gustenar]

Hello @TDW1

The arbiter is required for certain configurations and optional for others. The Administration Guide says: 

Follow these Arbiter guidelines:

•Arbiter is required for all clusters with two HPE OmniStack hosts.

•Arbiter is required for all stretched cluster configurations.

•HPE recommends using Arbiter in non-stretch cluster configurations with four HPE OmniStack hosts.

https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=a00126375en_us

Page 15.

The option means your Simplivity cluster has a number of nodes that don't require an arbiter to be installed. 

[whatlookfor]

Hello guys, following this discussion, i have one question about possible split brain scenario that i need to confirm.

I have to two nodes in one vmware cluster, one federation, each node at two different locations. Arbiter is located on a cloud VM that can be reached from both nodes obviously.

Questions :

• Is this deployment secure ?
• If i lose connection between arbiter and one host or both host = i guess everything's fine as long as hosts can communicate whith each other but if i lose network connection between the two nodes meaning each can only communicate with the cloud arbiter, would it create a split brain scenario or not ?
• Would it be better to leave the Arbiter next to a Simplivity node on the same location ?

Thanks for your help

DFi

[isvargase]

i have another question, is possible install the arbiter in the cloud, like azure o aws¡¡

[Sanika]

Hello @isvargase

Arbiter is designed to be installed on a separate physical or virtual machine within the same network as the HPE SimpliVity nodes. This setup is generally within on-premises environments or private clouds where the network latency and reliability can be tightly controlled.

According to my understanding, cloud environments like AWS or Azure might introduce network latency and variability that could impact the performance and reliability of the Arbiter. The arbiter needs a stable and low-latency connection to the SimpliVity nodes to function correctly.

I would suggest you to contact HPE support to get confirmation and guidance on deploying the SimpliVity Arbiter in a cloud environment.
If it is feasible, set up a test environment to evaluate the performance and reliability of the arbiter in the cloud before moving to a production setup.

Hope this helps.

Regards,
Sanika.

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[isvargase]

Oh thanks my friend i really appreciate it..
Regards



Isaac Vargas | Infraestructura de Datacenter

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