Windows Clustering

How to Achieve High Availability in Windows

To mitigate system downtime and ensure high availability for Windows, IT best practice recommends that you cluster servers (or nodes) so that if one node fails, one or more other nodes automatically take over processing. This is also referred to as Windows clustering.

To configure Windows clustering, you need clustering software that monitors the health of the primary node and initiates recovery actions if it detects an issue. HA clustering also requires a way to ensure that, in the event of a failure, the secondary node is accessing the most current versions of data in storage. In most cases, this is achieved by connecting all nodes of the cluster to the same shared storage. The cluster nodes should be separated geographically to ensure sitewide and regional disaster recovery (DR) protection.

In Windows Server environments, Microsoft includes Windows Server Failover Clustering (WSFC) in the Windows Server environment.

What is Windows Server Failover Clustering?

With WSFC, each active node has a standby node that has the same hardware specifications and shares the same storage. A third node is often configured as a “witness” server that ensures that, in the event of a communication failure between cluster nodes, operation continues on a single primary server. In addition to monitoring the health of the cluster, the nodes in a WSFC also work together to collectively provide:[1]

  • Resource management – Individual nodes provide physical resources such as SAN and network interfaces. The hosted applications are registered as a cluster resource and can configure startup and health dependencies upon other resources.
  • Failover coordination – Each resource is hosted on a primary node and can be automatically or manually transferred to one or more secondary nodes. Nodes and hosted applications are notified when failover occurs so that they can appropriately react. WSFC works with Microsoft Always On Availability Groups and Always On Failover Clustering to coordinate failover In Microsoft SQL Server environments.

How SIOS DataKeeper Complements WSFC

WSFC requires shared storage to ensure all cluster nodes are accessing the most up-to-date data in the event of a failover. Often, companies configure clusters using shared storage – typical SANs. However, SANs can be expensive to buy and manage and they represent a single point of failure risk. Shared storage clusters can also be extremely complex and costly to configure in some public clouds and are not an option in others.

SIOS DataKeeper Cluster Edition seamlessly integrates by eliminating the need for shared storage. It provides performance-optimized, host-based replication to synchronize local storage in all cluster nodes, creating a SANless cluster. While WSFC manages the cluster, SIOS DataKeeper performs synchronous or asynchronous replication of the storage giving the standby nodes immediate access to the most current data in the event of a failover. SIOS DataKeeper not only eliminates the cost, complexity, and single-point-of-failure risk of a SAN, but also allows you to use the latest in fast PCIe Flash and SSD in your local storage for performance and protection in a single cost-efficient solution.

With SIOS DataKeeper, you can also balance network bandwidth and CPU utilization for each application.

  • If fast replication is critical, SIOS DataKeeper can achieve more than 90 percent bandwidth utilization to accelerate data synchronization.
  • If minimizing network impact is your top priority, SIOS DataKeeper offers integrated compression and bandwidth throttling.

In addition, the SIOS DataKeeper Target Snapshots feature lets you run point-in-time reports from a secondary node to offload workloads that can impact performance on the primary node. This lets you query and run reports faster and make faster decisions.

Working with WSFC, SIOS DataKeeper Cluster Edition protects essential Windows environments, including Microsoft SQL Server, SAP, and SharePoint using your choice of industry-standard hardware and local attached storage in a “shared-nothing” or SANless configuration.[2] SIOS DataKeeper also provides high availability and disaster recovery protection for your business-critical applications in cloud environments, such as Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Services without sacrificing performance.

SIOS LifeKeeper – Protecting a Windows Environment Without WSFC

SIOS LifeKeeper for Windows is an alternative to WSFC that monitors the health of the entire application environment, including servers, operating systems, and databases. It can stop and restart an application both locally and on another cluster server at the same site or in another location. When a problem is detected, SIOS LifeKeeper automatically performs the recovery actions and automatically manages cascading and prioritized failovers.

SIOS LifeKeeper is sold in a purchasing bundle called SIOS Protection Suite for Windows that includes SIOS LifeKeeper, SIOS DataKeeper replication software and Application Recovery Kits for leading application and infrastructure operations. It is a tightly integrated clustering solution that combines high availability failover clustering, continuous application monitoring, data replication, and configurable recovery policies to protect your business-critical applications and data from downtime and disasters.

Distributed metadata and notifications

The WSFC service and node’s metadata/status are hosted on each node in the cluster. When changes occur on any node, updated information is automatically propagated to all other nodes. With SIOS Protection Suite, you can use your choice of SAN or SANless clusters using a wide array of storage devices, including direct-attached storage, iSCSI, Fibre Channel, and more. SIOS Protection Suite for Windows can meet your high availability and disaster recovery needs within a single site and across multiple sites.

SIOS Windows Clustering for SQL Server, SAP, S/4HANA, and Oracle

SIOS provides comprehensive SAP-certified protection for both applications and data, including high availability, data replication, and disaster recovery. To protect SAP in a Windows environment, SIOS LifeKeeper, monitors the entire application stack. SIOS protects your Oracle Database whether you are using it with SAP or running standalone Oracle applications – you simply select the Application Recovery Kit that matches your configuration.

Windows Clustering in the Cloud

Whether you need SIOS DataKeeper to enable Windows Server Failover Clustering in the cloud or SIOS Protection Suite for Windows for application monitoring and failover orchestration, as well as efficient, block-level data replication, SIOS delivers complete configuration flexibility. SIOS allows you to create a cluster in any combination of physical, virtual, cloud, or hybrid cloud infrastructures. For example, working with WSFC, SIOS DataKeeper can:

  • Protect essential on-premise or hybrid business applications to a high availability Windows environment in AWS, Azure, or Google Cloud.
  • Protect cloud applications, such as SQL Server and SAP, by creating a Windows cluster in AWS, Azure, or Google Cloud.
  • Provide site-wide, local, or regional high availability and disaster recovery protection by failing over application instances across cloud availability zones or regions.

SIOS DataKeeper Cluster Edition can provide high availability cluster protection across cloud

Protecting Windows Applications

SIOS provides offerings that support a breadth of applications, operating systems, and infrastructure environments, providing a single solution that can handle all your high availability needs. Here are just a few examples that demonstrate the power of SIOS.

  • Perth Stadium in Western Australia implemented SIOS DataKeeper with WSFC to provide high availability for their Hyper-V virtual machines.
  • PayGo (, based in the U.S., implemented SIOS DataKeeper with WSFC to provide high availability for SQL Server on AWS.
  • Toyo Gosei, based in Japan, implemented SIOS DataKeeper with WSFC to provide high availability and disaster recovery for their SAP application on Azure.