When virtualizing your file servers, the limiting factors are usually the storage I/O utilization and the network utilization. The maximum reported IOPS using VMWare is 102,240 and the maximum reported network performance is 16Gbps.
Here are Best practices for configuring virtual storage from VMWare Performance Team:
Many of the best practices for physical storage environments also apply to virtual storage environments. It is best to keep in mind the following rules of thumb when configuring your virtual storage infrastructure:
Configure and size storage resources for optimal I/O performance first, then for storage capacity.
This means that you should consider throughput capability and not just capacity. Imagine a very large parking lot with only one lane of traffic for an exit. Regardless of capacity, throughput is affected. It’s critical to take into consideration the size and storage resources necessary to handle your volume of traffic—as well as the total capacity.
Aggregate application I/O requirements for the environment and size them accordingly.
As you consolidate multiple workloads onto a set of ESX servers that have a shared pool of storage, don’t exceed the total throughput capacity of that storage resource. Looking at the throughput characterization of physical environment prior to virtualization can help you predict what throughput each workload will generate in the virtual environment.
Base your storage choices on your I/O workload.
Use an aggregation of the measured workload to determine what protocol, redundancy protection and array features to use, rather than using an estimate. The best results come from measuring your applications I/O throughput and capacity for a period of several days prior to moving them to a virtualized environment.
Remember that pooling storage resources increases utilization and simplifies management, but can lead to contention.
There are significant benefits to pooling storage resources, including increased storage resource utilization and ease of management. However, at times, heavy workloads can have an impact on performance. It’s a good idea to use a shared VMFS volume for most virtual disks, but consider placing heavy I/O virtual disks on a dedicated VMFS volume or an RDM to reduce the effects of contention.
Source: VMWare Performance Team
