When using ESXi with Fibre Channel SAN, follow best practices that VMware offers to avoid performance problems.
The vSphere Web Client offer extensive facilities for collecting performance information. The information is graphically displayed and frequently updated.
You can also use the resxtop or esxtop command-line utilities. The utilities provide a detailed look at how ESXi uses resources in real time. For more information, see the vSphere Resource Management documentation.
Check with your storage representative if your storage system supports Storage API - Array Integration hardware acceleration features. If it does, refer to your vendor documentation for information on how to enable hardware acceleration support on the storage system side. For more information, see Storage Hardware Acceleration.