There's no doubt that licensing is one of the trickiest aspects of any Microsoft product to figure out. SQL Server licensing is certainly no exception. In fact, it's often harder to figure out the licensing than it is to figure out how to use the different technical product features. Some of the changes in SQL Server 2012 have made licensing decisions more difficult than ever. Major factors that make SQL Server 2012 licensing confusing are the changes in editions, the new core-based licensing, and the different availability options that are brought about by new features such as AlwaysOn Availability Groups. In addition, you might wonder how the new core licensing affects fault-tolerant systems that have duplex hardware. Let's take a closer look at some of the more confusing SQL Server 2012 licensing issues.

Editions and Licensing

Server 2012 includes several new licensing changes. For example:

  • SQL Server 2012 Enterprise is licensed only per core
  • SQL Server 2012 Business is licensed only per server and CAL
  • SQL Server 2012 Standard can be licensed either per core or per server and CAL

SQL Server 2012's licensing requires that you buy a minimum of four core licenses. You can purchase additional core licenses in packs of two. When you implement SQL Server 2012 in a virtual machine (VM), each virtual processor equates to a core. For example, if you license SQL Server 2012 Standard per core and install it onto a VM with four virtual processors, then you need to buy four core licenses. The only exception to this is if you buy SQL Server 2012 Enterprise and then license all of the cores on the physical machine. Then you can run an unlimited number of SQL Server instances in VMs on that host. It doesn't matter if it's a Microsoft Hyper-V host or a VMware vSphere host.

You might not realize that there are licensing limitations to moving VMs. OEM licenses can be moved only once every 90 days—which isn't very conducive to creating a dynamic data center. To be able to frequently move a VM, you must have the license covered by Software Assurance (SA). Therefore, SA is a requirement if you're thinking of moving toward the dynamic data center or private cloud

Availability Options and Licensing

Licensing for high availability with Failover Clustering and AlwaysOn Availability Groups can be confusing as well. With Failover Clustering, if one server fails, its processing will be picked up by another server in the cluster. SQL Server 2012's new AlwaysOn Availability Groups feature lets you implement both synchronous and asynchronous database replication for high availability and disaster recovery. Plus, it has the added advantage of enabling the replica databases to be accessed for reporting and backup.

Both Failover Clustering and AlwaysOn Availability Groups allow you to skip licensing the backup server if it is truly passive (i.e., only used when the primary system isn't active). However, there's no such thing as a free lunch, and it might go without saying, but customers who use Failover Clustering and/or AlwaysOn Availability Groups will have to pay for SQL Server licenses on all of the SQL Server systems that are active. If you use those standby servers in your AlwaysOn Availability Groups for reporting or even just for performing backups, then they must have a full SQL Server 2012 license. Likewise, if you use the backup nodes in your failover cluster for any kind of SQL Server database work while the primary node is active, then it must also be licensed.

Finally, you might wonder about licensing for high-availability hardware servers such as the fault-tolerant Stratus ftServer systems or the NEC Express5800 line of servers. Because these types of fault-tolerant servers use redundant hardware, does that mean you need to double the licensing costs? For these solutions, the answer is no. Despite the dual hardware, Microsoft considers these as single systems, and there's no need to license the redundant hardware.

You can learn more about SQL Server 2012 licensing from Microsoft's How To Buy: Comprehensive Licensing Information for SQL Server 2012 page and from Microsoft's "SQL Server 2012 Licensing Quick Reference Guide." You can also check out the license costs for various Microsoft products using the Microsoft License Advisor.