first of all iscsi dont need any separate vlans for each iscsi target ports, that is a single vlan is enough.
Here you have total 8 ports in the iscsi storage side, and you need to have 8 pnics and 8 vmkernel ports in the esx side, then only you will get the full bandwidth. that is there should be an end to end mapping, that is one esxi vmkernek ip to ine storage target ip.
else you need to use etherchannel or LAG