sounds to me it is still a compatibility problem even tho they said its compatible as when you install it on main site it does the problem and on Dr its not then the device is completely ok but the problem is in the environment on main site . Let try doing an esxtop to identify storage performance issues for ESX / ESXi the interactive esxtop utility can be used to provide I/O metrics over various devices attached to a VMware ESX host. and in this KB you will find exactly how to do it http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1008205 Let me know if you need any more help Best regards
Your Oscar