This article provides steps to test the speed/throughput on ESX/ESXi and virtual machines as well as steps to narrow down the issue.

Doing speeds tests are always relative to the environment and hardware being used.
 

This article cannot provide specific test result numbers to expect as every environment is unique and the total load for an array is different.
 

You must establish a baseline throughput. You need to make an apples to apples comparison between an ESX host running a single virtual machine and a physical host. If the hardware between the two are identical and the operating system version between the physical host and the virtual machine are also the same, these two systems perform as close to each other as possible. If they do not perform similarly, other factors (BUSlogic vs. LSIlogic) need to be taken into consideration to explain the difference.

 

To establish a baseline:

 

The results must be similar. If they are not, you need to review why.
 

Possible factors include:

If the virtual machine is not performing well, review /var/log/vmkernel for possible reasons for this degradation. If both the physical host and virtual machine are performing poorly but identically, review the array and switch configuration.
 

A possible reason for equally poor performance may be write cache on the array controllers or over commitment of the array in general.
 

 

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