The VMware vSphere hypervisor version 7.0 adds two scale improvements to meet the demands of high-performance databases like Oracle:
The ESXi scheduler is optimized for latency-sensitive workloads. To take advantage of this optimization, you must identify the VM as latency-sensitive by using a setting in the configuration.
VMware developed paravirtual SCSI controller technology to optimize storage performance by enabling greater I/O operations and reducing the load on the host processor. For Oracle databases, using the PVSCSI has been a long-standing best practice when configuring a virtual machine for storage performance.
We recommend using PVSCSI if the storage array uses faster storage technologies like SSD. The advantage of the NVMe controller is that it reduces software overhead for processing guest operating system I/O. A study, , shows that for databases, the NVMe controller increased IOPS, increased throughput (MB/s), and lowered latency (millisecond). If your PowerStore system has NVMe or Intel Optane Storage Class Memory (Pmem), we recommend that you use the NVMe controller.
Automatic Storage Management (ASM) is an Oracle feature that was released with Oracle 10g. Using ASM simplifies the management of database datafiles, control files, and log files. Raw device mapping (RDM) provides a mechanism by which a virtual machine can have direct access to a LUN on the physical storage subsystem. For our tests, all ASM disks were provisioned on volumes using RDM. Recent studies have shown that there is a negligible difference in performance between VMware File System (VMFS) and RDM. VMware recommends using VMFS for most applications including databases. If you are considering using RDMs for your deployment, you must understand that the maximum number of RDM connections to LUNs for one ESXi host is 256.