Failover Clustering - Google Cloud

Introduction of Failover Clustering

• It is a group of servers that work to maintain the high availability services and applications.

• If one of the servers, or nodes fails, another node in the cluster can take over its workload without any downtime, this is called failover.

• It is widely used in Windows Server on Google Cloud Platform (GCP). If a cluster node fails then another node can take over running the software applications.

Architecture

This is an architecture example of failover clustering. The example system contains the following three servers:

• Primary compute engine of VM instances running Windows Server 2016.

• Second instance, configured to match the primary instance.

• An AD domain name server (DNS). This server:

• Provides a Windows domain.

• Resolves hostnames to IP addresses.

• Hosts the file share witness

Objectives

• Create a network.

• Install Windows Server 2016 on two Compute Engine VMs.

• Install and configure Active Directory on an instance of Windows Server.

• Setup the failover cluster and including a file share witness for the quorum and a role for the workload.

• Setup the internal load balancer phase.

• Test all tasks of failover operation to verify that the cluster is working.

Why Failover Clustering

• HA (High Availability) file share storage for applications such as Microsoft SQL Server and Hyper-V virtual machines

• In this Highly available clustered roles that run on physical servers or on virtual machines that are installed on servers running Hyper-V.

What happens during a failover

• In this Windows failover cluster changes the status of the active node to indicate that it has failed.

• Failover clustering moves any cluster resources and roles from the failing node to the best node, as defined by a quorum. This action includes moving the associated IP addresses.

• Failover clustering broadcasts the ARP packets to notify hardware-based network routers that the IP addresses have moved. For this scenario, GCP networking ignores these packets.

• After that, this Compute Engine agent on the VM for the failing node changes its response to the health check from 1 to 0, because the VM no longer hosts the IP address specified in the request.

• This Compute Engine agent on the VM for the newly active node likewise changes its response to the health check from 0 to 1.

• The internal load balancer stops route traffic to the failing node and instead routes traffic to the newly active node.

Advance features of Failover Clustering

• Cluster Operating System Rolling Upgrade - It enables the operating panel to upgrade the operating system of the cluster nodes from Windows Server 2012 R2 to a newer version without stopping the Hyper-V or Scale-Out File Server workloads.

• Storage Replica - It is a new feature that enables storage-agnostic, block-level, synchronous replication between servers or clusters for disaster recovery, as well as stretching of a failover cluster between sites.

• Cloud Witness - It is a new type of Failover Cluster quorum witness in Windows Server 2016 that leverages Microsoft Azure as the arbitration point.

• Virtual Machine Load Balancing - It facilitates the seamless load balancing of virtual machines across the nodes in a cluster. These nodes are identified based on virtual machine Memory and CPU utilization on the node.

• Workgroup and Multi-domain clusters - Windows Server 2016 breaks down these barriers and introduces the ability to create a Failover Cluster without Active Directory dependencies. Create failover clusters in the following configurations:

• Single-domain Clusters - All cluster nodes joined to the same domain.

• Multi-domain Clusters - Clusters nodes which are members of different domains.

Workgroup Clusters - Clusters with nodes which are member servers or workgroup.