The following configuration items should be considered:
- Use multiple VMware Paravirtual (PVSCSI) vSCSI controllers to connect virtual disks hosting applications / databases related data (including logs and tempdb). PVSCSI is a high-performance storage adapter that provides better throughput and lower CPU utilization for VMs. It is best suited for environments where guest applications are very I/O intensive.
- Use multiple PVSCSI controllers (up to four) to balance the disk throughput between controllers.
- Consider to place disks with latency sensitive, synchronous traffic on a separate PVSCSI controller
- Consider a multiple VMDK disk layout to redistribute load between vSAN nodes. This is especially important as vSAN is much more efficient with smaller disks, so a VM with multiple smaller in size VMDKs distributed between multiple vSCSI controllers is expected to perform better compared to a VM with the same workload but using just a single VMDK on a single vSCSI Controller.
- Increasing the PVSCSI controller queue length in guest operating system might have a positive impact on the disk throughput for your application. Consult this kb article for more details.
- Consider setting the Object Space Reservation (OSR) Advanced Policy Setting to “Thin provisioning”. OSR controls only the space reservation and has no performance advantages. While the control over capacity is still very important for on-premises solutions, on VMware Cloud on AWS Elastic DRS (eDRS) ensures the cluster will not run out of free capacity. You can check this blog article for more details.