Host has lost connection to a storage device that backs a VMFS datastore or a datastore extent.
This event is logged when an host loses connection to storage.
Either a storage device that backs an entire datastore is offline, or one of the extents is offline. Virtual machines that use that storage may become unresponsive or fail.
Locate the device that has failed and restore connectivity. Check cabling and switch connections. Refer to this VMware KB article for further details.