How to Stack SQL Server Instances: Because 1 Instance Per Machine is Just Plain Wasteful

Stacking can be scary, there’s no denying that. Whether it’s the most recent Jenga piece you pulled out of the foundation of your tower, or a bunch of heavy-duty SQL Server instances, things can spiral out of control quickly.

For many years, industry convention remained stubbornly fixed on the idea of only mapping 1 SQL Server instance per machine. There were certainly logical reasons for this:

  • Fear of the machine going down—knowing it would affect all hosted instances
  • Logistical complications when going through modernization and maintenance tasks
  • Fear of not meeting SLAs as multiple instances on one box continue to organically grow
  • Risk of getting stacking ratios wrong, and having to laboriously migrate instances one at a time—all while dealing with changing application connection strings

Windows Server Failover Clustering FCIs starts to enable safe stacking, but you have to pay up for Enterprise Edition SQL Server if you want a cluster with greater than 2 nodes. This still doesn’t mitigate the inherent challenges of WSFC though. Initial configuration, troubleshooting, and management can be huge pain points, and WSFC doesn’t allow you to manage existing workloads. Instead, you must create a brand new cluster and migrate to it.

For nearly a decade now, DxEnterprise Smart Availability software has been unlocking the most unparalleled instance-stacking experience in the industry. It does this by leveraging standalone instances—decoupling them completely from the underlying infrastructure. This enables DH2i’s advanced HA engine to provide bulletproof protection at the instance level. Additional QoS controls mean you can ensure SLAs will be continuously met, and DxEnterprise will take automated action—if necessary—to quickly move instances from host to host with a simple application stop-start.

In total, along with the potential to save you a significant amount of money on licensing costs, DxEnterprise unlocks some very unique benefits like:

  • Clusters of 3+ nodes on ANY edition
  • Clusters of mixed OS/SQL versions
  • The ability to manage existing workloads
  • Drag and drop modernization of infrastructure, OS, and application version

If you’re curious about the solution, we encourage you to sign up for a free one-on-one demo or free trial. You can also reach out to with any questions you have.


Lauren Hawes