IT organizations consolidate servers and storage arrays in data centers to control costs and limit data center expansion. Consolidating databases is more complex, however, because of their dependencies and performance requirements. In validating and testing this architecture, we followed proven strategies for consolidating databases.
Virtualization enables the isolation of disparate applications and granular management of server and storage resources. Therefore, all the virtualized databases can have different versions of operating systems and database engines without having an impact on each other. Virtualization facilitates consolidation and enables more efficient use of server and storage resources. We used vSphere 6.7 as the virtualization layer for consolidating the SQL Server databases, as described in Multipathing configuration.
In our tests, virtualization was used to reserve CPU resources per VM. In vSphere, a reservation for CPU or memory means that the VM is guaranteed that server resource. For example, each VM in our tests had a vCPU reservation of 16 virtual cores, meaning that this is the minimum acceptable amount of processor resources for the VM. The average peak processor utilization was 58.6 percent for the Windows server VMs and 41.2 percent for the Linux VMs. Figure 12 shows that average peak utilization for both Windows and Linux left significant unused processor resources for additional workloads on the PowerEdge R840 servers.
One strategy is to lower the number of reserved vCPUs on the server and monitor the VMs. The benefit of lowering the amount of vCPU resources is reducing the possibility of CPU resource contention. Customers have been successful with using a strategy of lowering vCPU reservations and increasing memory reservations, thus gaining more performance. We highly recommend that you use monitoring tools to collect and analyze changes in server resources for virtualized databases to determine if this strategy works.
The other benefit of looking for opportunities to save on CPU resources is the capability to maximize use of system resources and achieve even higher consolidation ratios. In the case of the PowerEdge R840 server tests, results show a consolidation ratio of eight virtualized SQL Server databases to each server. Additional testing, reducing the vCPU reservations on the VMs, can determine if the servers can support more databases.