Tag: Failover Cluster

Nested Virtualized Windows Server 2016 Hyper-V Cluster LAB – Scenario 2

This Scenario will be lot quicker and we will be using PowerShell since Nano Server is without GUI and it will definitely reflect on footprint and size of cluster.

I recommend you read Nano Server – Deployment since I will be using that procedure for creating script that will automate creation of Nano Servers.

In this scenario we will have 3 VMs and first one same as in Scenario 1 will be VM with our Domain Controler, DHCP, DNS and we will need to setup all those services on that VM(detailed info on this procedure). This time we will also need to install Failover Cluster Manager so we can manage Nano servers since they don’t have any GUI. Second and Third will be our Nano Servers that we will create with script below but before we do it we need to mount Windows Server 2016 ISO  and copy NanoServer folder to our C: drive.

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Failover Cluster Quorum

This topic aims to explain the Quorum configuration in a Failover Clustering.

What’s a Failover Cluster Quorum

A Failover Cluster Quorum configuration specifies the number of failures that a cluster can support in order to keep working. Once the threshold limit is reached, the cluster stops working. The most common failures in a cluster are nodes that stop working or nodes that can’t communicate anymore.

Imagine that quorum doesn’t exist and you have two-nodes cluster. Now there is a network problem and the two nodes can’t communicate. If there is no Quorum, what prevents both nodes to operate independently and take disks ownership on each side? This situation is called Split-Brain. Quorum exists to avoid Split-Brain and prevents corruption on disks.

The Quorum is based on a voting algorithm. Each node in the cluster has a vote. The cluster keeps working while more than half of the voters are online. This is the quorum (or the majority of votes). When there are too many of failures and not enough online voters to constitute a quorum, the cluster stop working.

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