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To achieve a meaningful test result for a single R750xs server, four virtualized databases were run in parallel. After several tests using HammerDB and an OLTP workload, a baseline configuration was developed. The following table shows the vCPU and memory allocation for each virtualized database:
Table 5. vCPU and memory allocation
Resource reservation | Baseline configuration per virtual machine | Total across four virtualized databases |
vCPU | 16 cores | 64 cores |
Memory | 128 GB | 512 GB |
A VMware reservation is a guaranteed allocation of CPU or memory for the virtual machine. In the case of the vCPU, each virtual machine received a 16-core reservation. With four total virtualized databases, the total vCPU reservation was 64-cores (four virtual machines each with sixteen cores) on the server. The PowerEdge R750xs servers are two socket servers and in the configuration for our tests, two Intel® Xeon® Gold 6338 CPUs were used. Each Intel® CPU has 32 cores so there was a total of 64 physical cores.
While the virtual machines used 64 physical cores by default, the PowerEdge R750xs servers enable logical processors. When logical processors are enabled, the hypervisor presents twice as many processor cores. In our configuration the 64 physical processor cores are presented as 128 cores (64 x 2). Logical processors can boost performance by enabling more processes in parallel. In the case of our four virtual databases, we used 64 of the available logical processor cores from the total available of 128 logical processor cores.