Ideally, turning off defrag at the VM level is the way to go. Especially for arrays that have flash utilized as a tier in a storage pool --- defragging is one of the worst things to do to flash cells.  You will be better suited to ensure that disk alignment is properly configured at the VMFS/ESXi level (VMFS volumes are automatically aligned when formatted using the GUI/vSphere client) and the OS level (Windows 2008 and newer automatically align the offset to 1 MB).
What is the best practice for defragging vms stored on vnx5300?  Thanks in advanced.
Best practice for defragging vms stored on vnx5300