Home > Workload Solutions > Oracle > White Papers > Oracle Database 19c Best Practices on Dell PowerEdge Servers and PowerStore T Model Arrays > Memory reservation
The memory configuration per virtual machine included a reservation of 128 GB. A total of 512 GB of memory was reserved using four virtual machines. The virtual machines used half of the available physical memory in the server, leaving 1 TB available memory in the server. In allocating memory to each virtual machine, the goal was to ensure each VM fit into a physical non-uniform memory access (NUMA) node. NUMA refers to a multiprocessor configuration in which each physical CPU has a dedicated memory bank. Information can be retrieved faster from the local memory bank than having to pull the data from another memory bank. When a virtual machine’s memory spans two memory banks, wait times are incurred, causing sub-optimal performance.
To prevent this sub-optimal NUMA design, each virtual machine has been allocated 128GB of memory, thus enabling the use of only the local memory bank. The VMware ESXi hypervisor is responsible for the placement of memory on a processor and has been designed to optimize performance. By reserving memory that enables the virtual machine to use a local memory bank we have optimized performance for all the virtual machines on the server.