A number of restrictions exist when you use ESXi with an iSCSI SAN.
ESXi does not support iSCSI-connected tape devices.
You cannot use virtual-machine multipathing software to perform I/O load balancing to a single physical LUN.
ESXi does not support multipathing when you combine independent hardware adapters with either software or dependent hardware adapters.
ESXi does not support IPv6 with software iSCSI and dependent hardware iSCSI.