All permissions for the export are correct on the VNX for the hosts being denied. If IPv6 is enabled on the ESXi host, mount permission is always denied. Simply disabling IPv6 on the host bypasses the problem: VNX will allow the mount to succeed. Has anyone seen this? I see this with ESX 5.1 and 5.5. Failure occurs using SRM with the VNX SRA, or even manually mounting via the vSphere Client.
FYI... There is an issue in which VNX systems may experience a storage processor (SP) reboot when IPv6 network devices are present in the management or iSCSI LAN. The cause is due to the network driver that is used on the array does not properly handle padding if applied by an external IPv6 network device in the extended header segment of the IPv6 Neighbor Discovery Protocol (NDP) packet.