How works replication in a 3 node cluster?

Evidian SafeKit provides a 3 node cluster with replication and failover on Windows and Linux. This feature is an extension of a mirror cluster with replication of data on a third server supposed to be in a Disaster Recovery site (DR Site).

Windows File Replication and Windows Clustering between 3 Servers Architecture

How to implement replication in a 3 node cluster?

2 SafeKit modules are required for implementing replication in a 3 node cluster : the application module and the spare module.

The application module works between server 1 and server 2 as a standard mirror module with

  • synchronous or semi-synchronous real-time replication of application directories,
  • when server 1 fails, automatic application failover to server 2,
  • when server 1 restarts, automatic failback with reintegration of directories

With the semi-synchronous real-time replication between server1 and server2, the application does not wait the acknowledgement of server3 before restarting its execution.

The other module (named the spare module) makes the real-time replication to the DR site.

Windows File Replication and Windows Clustering between 3 Servers Implementation

How to install a 3 node cluster with replication and failover?

An application module named 3nodesrepliv2.safe has been developed as an extension of the mirror module to simplify the installation. And the SafeKit web console helps in the deployment of this module on 3 servers.

Windows File Replication and Windows Clustering between 3 Servers Installation 1

In the configuration wizard of 3nodesrepliv2.safe, the identity of the 3 servers are entered.

Windows File Replication and Windows Clustering between 3 Servers Installation 2

In the configuration, the path of the directory to replicate is set.

Windows File Replication and Windows Clustering between 3 Servers Installation 3

Among the 3 servers, the server in the disaster recovery site must be identified.

Windows File Replication and Windows Clustering between 3 Servers Installation 4

The first time, the server with the up-to-date data must be identified in order to synchronize data in the right way.

Windows File Replication and Windows Clustering between 3 Servers Installation 5

Finally, the system is high available
  • with automatic restart of the critical application thanks to the application module (named 3nodesrepli in the picture)
  • with a real-time replication of data on the third node thanks to the spare module (named 3nodesrepli_spare in the picture).

Windows File Replication and Windows Clustering between 3 Servers Installation 6

Failover to the disaster recovery site

When server 1 and server 2 fail, the application failover to the DR site is possible with a manual procedure integrated in the administration console.

Windows File Replication and Windows Clustering between 3 Servers - Failover to the Disaster Recovery site

Failback from the disaster recovery site

When server 1 and server 2 come back, the application failback from the DR site to server 1 and server 2 is possible with a manual procedure in the administration console.

Windows File Replication and Windows Clustering between 3 Servers Failback

SafeKit Modules for Plug&Play High Availability Solutions

SafeKit miror and farm high availability modules

SafeKit HA cluster architectures

Free high availability farm modules

Deploy a farm module on N servers.
And implement a network load balancing cluster with application failover.
The target is an application with web services to load balance between servers and with an automatic restart in case of failure.

Click on the blue buttons for a full description of the solution and a step-by-step installation procedure

Farm modules (load balancing and failover)

Windows

Linux

IIS module-
Apache module
Generic farm module for any application
Amazon AWS farm
Microsoft Azure farm
Google GCP farm
Cloud generic farm

Free high availability mirror modules

Deploy a mirror module on 2 servers.
And implement a mirror cluster with real-time file replication and application failover.
The target is an application with a database or flat files to replicate and with an automatic restart in case of failure.

Click on the blue buttons for a full description of the solution and a step-by-step installation procedure

Mirror modules (replication and failover)

Windows

Linux

Microsoft SQL Server-
Oracle
MySQL
PostgreSQL
Firebird
Hyper-V-
Milestone XProtect (based on Microsoft SQL Server)-
Hanwha Wisenet SSM (based on PostgreSQL)-
Generic mirror module for any application
Amazon AWS mirror
Microsoft Azure mirror
Google GCP mirror
Cloud generic mirror

Demonstrations of SafeKit High Availability Software

SafeKit Webinar

This webinar presents in 10 minutes Evidian SafeKit.

In this webinar, you will understand:

  • mirror and farm clusters
  • cost savings against hardware clustering solutions
  • best use cases
  • the integration process for a new application

Microsoft SQL Server Cluster

This video shows a mirror module configuration with synchronous real-time replication and failover.

The file replication and the failover are configured for Microsoft SQL Server but it works in the same manner for other databases.

Free trial here

Apache Cluster

This video shows a farm module configuration with load balancing and failover.

The load balancing and the failover are configured for Apache but it works in the same manner for other web services.

Free trial here

Hyper-V Cluster

This video shows a Hyper-V cluster with full replications of virtual machines.

Virtual machines can run on both Hyper-V servers and they are restarted in case of failure.

Free trial here