Microsoft SQL Server has become a business-critical database for a growing number of enterprises that rely on it to run a wide range of essential business processes. As enterprises look to continuously improve the efficiency of their data centers, they face the challenges involved in improving their ability to provide high availability and disaster protection for SQL Server.

A common strategy for providing high availability protection for SQL Server is to use AlwaysOn Availability Groups, a high availability feature included with SQL Server 2012 Enterprise Edition. It is positioned as an evolution of SQL Server Database Mirroring and an alternative to AlwaysOn Failover Clustering.

You can also use AlwaysOn Failover Clustering, which is included in both the SQL Server Enterprise and Standard Editions. While AlwaysOn Failover Clustering allows you to create a cluster in a physical server environment, it requires shared storage, which is not available in a cloud environment, and may not be practical in a virtual server environment. A third option is to add SANLess clustering software to AlwaysOn Failover Clustering. SANLess clustering provides high availability and more comprehensive data protection for a fraction of the cost of AlwaysOn Availability Groups which requires the very expensive Enterprise Edition of SQL Server

SANLess clustering software is an ingredient that enhances a Windows Server Failover Clustering (WSFC) environment by providing real-time, block-level replication to synchronize local attached storage. The resulting synchronized storage appears to WSFC as a virtual SAN, enabling you to create a SANLess cluster that eliminates the cost, complexity, and single point of failure risk of a SAN. SANLess clusters also help you save money and enhance availability in a variety of ways.

1. Use SQL Server Standard Edition with AlwaysOn Failover Clustering to Save Licensing Costs.

AlwaysOn Availability Groups requires SQL Server 2012 Enterprise Edition. SANLess clustering software lets you use AlwaysOn Failover Clustering, which is included in both Standard and Enterprise Editions of SQL Server as a more cost-efficient failover and disaster protection solution.

Figure1 shows a side-by-side comparison of software licensing costs for a traditional cluster using AlwaysOn Availability Groups to protect SQL Server Enterprise Edition versus a SANLess cluster using AlwayOn Failover Clustering and SANless clustering software (SIOS DataKeeper™ Cluster Edition) to protect SQL Server Standard Edition.

Costs are calculated for comparable two-node clusters with four, eight, and sixteen cores. Software Assurance licensing costs are also included. As shown, the SANLess cluster saves $13,124 in a four-core cluster, $33,448 in an eight-core cluster, and $74,096 in a 16-core cluster configuration. These savings include the purchase of SANLess clustering software, which is licensed per node. When used in multiple SQL Server environments, SANLess clusters can save several hundred thousand dollars in software licenses.

Figure 1 – Cost Comparison of Different High Availability Solutions

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