Flow Control on Storage network across trunk and on storage array interfaces

Hi,

I am new to storage networking so please forgive me if my terminology is off a bit.

I have a MXL-10/40GbE with several slots hosting vCenter.  I have a port channel connecting to S4048-ON.  This is where my storage arrays connect, specifically a trunked (port channel) Supermicro and a non trunked Dell 4084 PowerVault.

Doing backups we are haven lots of failed VMs (the interfaces don't look saturated) so here are my questions.

The vCenter hosts are the initiator in my iSCSI network, correct? 

The Supermicro and Dell 4084 PowerVault are the target in my iSCSI network, correct?

 

I believe the above questions are right and if they are:

How do I properly implement flow control?

Below is an example of my devices interface and how they are connected:

 

MXL-10/40GbE (Stacked)

interfaces to vCenters

TenGigabitEthernet 0/1 YES up up Server_Slot_1_vCenter
TenGigabitEthernet 0/2 YES up up Server_Slot_2_vCenter
TenGigabitEthernet 0/3 YES up up Server_Slot_3_vCenter
TenGigabitEthernet 0/4 YES up up Server_Slot_4_vCenter

TenGigabitEthernet 1/1 YES up up Server_Slot_1_vCenter
TenGigabitEthernet 1/2 YES up up Server_Slot_2_vCenter
TenGigabitEthernet 1/3 YES up up Server_Slot_3_vCenter
TenGigabitEthernet 1/4 YES up up Server_Slot_4_vCenter

interfaces for my port channel to my dell 4048-ON

TenGigabitEthernet 0/43 YES up up To_S4048-ON_Te2/46
TenGigabitEthernet 0/44 YES up up To_S4048-ON_Te1/46
TenGigabitEthernet 0/51 YES up up To_S4048-ON_Te1/45
TenGigabitEthernet 0/52 YES up up To_S4048-ON_Te2/45

TenGigabitEthernet 1/43 YES up up To_S4048-ON_Te2/48
TenGigabitEthernet 1/44 YES up up To_S4048-ON_Te1/48
TenGigabitEthernet 1/51 YES up up To_S4048-ON_Te1/47
TenGigabitEthernet 1/52 YES up up To_S4048-ON_Te2/47

and its port channel to the S4048-ON

Port-channel 1 YES up up To_S4048-ON

 

S4048-ON

interfaces to storage arrays

TenGigabitEthernet 1/21 YES up up To-Dell_4084
TenGigabitEthernet 1/22 YES up up To-Dell_4084
TenGigabitEthernet 1/23 YES up up To-Dell_4084
TenGigabitEthernet 1/24 YES up up To-Dell_4084

TenGigabitEthernet 2/21 YES up up To-Dell_4084
TenGigabitEthernet 2/22 YES up up To-Dell_4084
TenGigabitEthernet 2/23 YES up up To-Dell_4084
TenGigabitEthernet 2/24 YES up up To-Dell_4084

TenGigabitEthernet 1/11 YES up up To_Supermicro
TenGigabitEthernet 1/12 YES up up To_Supermicro

TenGigabitEthernet 2/11 YES up up To_Supermicro
TenGigabitEthernet 2/12 YES up up To_Supermicro

and its port channel to the S4048-ON

Port-channel 2 YES up up Supermicro

Do I add the command:

flowcontrol rx on tx off

or

flowcontrol rx on tx on

I have read white papers on both ways

Do I the command to all my vCenter hosts and both sides of my port channel and my two storage arrays?

 

Thanks in advance for every ones help.