Hot Add CPU
Hot add CPU is the ability to dynamically add CPUs to a running system. Adding CPUs can occur physically by adding new hardware, logically by online hardware partitioning, or virtually through a virtualization layer. Starting with SQL Server 2008, SQL Server supports hot add CPU.
Requirements for hot add CPU:
Requires hardware that supports hot add CPU.
Requires the 64-bit edition of Windows Server 2008 Datacenter or the Windows Server 2008 Enterprise Edition for Itanium-Based Systems operating system.
Requires SQL Server Enterprise.
SQL Server cannot be configured to use soft NUMA. For more information about soft NUMA, see Understanding Non-uniform Memory Access, and How to: Configure SQL Server to Use Soft-NUMA.
SQL Server does not automatically start to use CPUs after they are added. This prevents SQL Server from using CPUs that might be added for some other purpose. After adding CPUs, execute the RECONFIGURE statement, so that SQL Server will recognize the new CPUs as available resources.
If the affinity64 mask is configured, the affinity64 mask must be modified to use the new CPUs.