Shared nothing cluster vs shared disk cluster

Evidian SafeKit

Comparison between a shared nothing cluster vs a shared disk cluster

Shared nothing cluster vs shared disk cluster is an important point to consider when choosing a cluster solution. The deployment of a shared nothing cluster as implemented by SafeKit is much more simple than a shared disk cluster.

Simplicity of a shared nothing vs a shared disk cluster

Shared nothing cluster

Cluster sans partage

Shared disk cluster

Cluster avec disques partagés

Product

SafeKit on Windows and Linux

Clustering toolkit for shared disk

Extra hardware

No - Use internal disks of servers

Yes - Extra cost with a shared bay of disks

Application data organization

0 impact on application data organization with SafeKit.

Just define directories to replicate in real-time.

Even directories inside the system disk can be replicated.

Impact on application data organization.

Special configuration of the application to put its data in a shared disk.

Data in the system disk cannot be recovered.

Complexity of deployment

No - install a software on 2 servers

Yes - require specific IT skills to configure OS and shared disk

Failover

Just restart the application on the second server.

Switch the shared disk.

Remount the file system.

Pass the recovery procedure on the file system.

And then restart the application.

Disaster revovery

Just put the 2 servers in 2 remotes sites connected by an extended LAN.

Extra cost with a second bay of disks.

Specific IT skills to configure mirroring of bays across a SAN.

Quorum and split brain

Application executed on a single server after a network isolation (split brain).

Coherency of data after a split brain.

No need for a third machine or a quorum disk or a special heartbeat line for split brain.

More information on heartbeat, failover and quorum

Require a special quorum disk or a third quorum server to avoid data corruption on split brain

Suited for

Software editors which want to add a simple high availability option to their application

Enterprise with IT skills in clustering and with large database applications

Video comparing a shared disk cluster and a shared nothing cluster when considering disaster recovery

SafeKit: an ideal solution for a partner application

This platform agnostic solution is ideal for a partner with a critical application and who wants to provide a high availability option easy to deploy to many customers.

SafeKit Modules for Plug&Play High Availability Solutions

SafeKit Modules for Plug&Play High Availability Solutions

Network load balancing and failover

Windows farm

Linux farm

Generic farm   > Generic farm   >
Microsoft IIS   > -
NGINX   > NGINX   >
Apache   > Apache   >
Amazon AWS farm   > Amazon AWS farm   >
Microsoft Azure farm   > Microsoft Azure farm   >
Google GCP farm   > Google GCP farm   >
Other cloud   > Other cloud   >

Note:

Several modules can be deployed on the same cluster. Thus, advanced clustering architectures can be implemented:

Demonstrations of SafeKit High Availability Software

SafeKit Webinar

This webinar presents in 2 minutes Evidian SafeKit.

In this webinar, you will understand SafeKit mirror and farm clusters.

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