By creating multiple VMKernel NICs it makes it possible to have multiple paths to iSCSI SAN storage and utilize MPIO.

However to do this and implement certain performance tweaks this has to be done partly via the GUI and partly via the service console. Hopefully in the future VMware will implement additions to the GUI to allow this.

While you may have several physical network adaptors connected to a vSwitch (in this case a distributed vSwitch - DVS), the VMkernel ports are required to make different connections/sessions to the iSCSI SAN storage device(s).

In this case it is used to configure MPIO via ESX 4 and a Dell EqualLogic PS SAN array. However the process should be similar if not the same for other vendor iSCSI SAN storage.

1. Set physical switch ports to MTU 9000

For example on Cisco 3750/3560 switches:

3750(config)# system mtu jumbo 9000
3750(config)# exit
3750# reload

 
 
2. Set DVS to MTU 9000
In vCenter go to Home --> Networking.

Create or click on the Distributed Virtual Switch (DVS) that is being used for ISCSI storage.

 
 
3. Create VMKNICs via GUI (Defaults to MTU 1500)

How to create a VMKernel port.

If you already have created 1 or more VMkernel ports continue...

4. Logon to the ESX service console and list the VMkernel interfaces.

Take note of the IP addresses.
 
/usr/sbin/esxcfg-vmknic -l
Interface  Port Group/DVPort   IP Family IP Address                              Netmask         Broadcast       MAC Address       MTU     TSO MSS   Enabled Type
vmk0       56                 IPv4      10.1.1.50                            255.255.255.0 10.1.1.255    00:50:56:3b:02:8c 1500    65535     true    STATIC
vmk1       57                 IPv4      10.1.1.51                            255.255.255.0 10.1.1.255    00:50:56:37:09:82 1500    65535     true    STATIC
vmk2       58                 IPv4      10.1.1.52                            255.255.255.0 10.1.1.255    00:50:56:3c:6e:72 1500    65535     true    STATIC
vmk3       59                 IPv4      10.1.1.53                            255.255.255.0 10.1.1.255    00:50:56:3d:ef:7d 1500    65535     true    STATIC

5. List the vSwitch details
Take note of the DVPort ID for each VMKernel (vmk#) NIC

 
/usr/sbin/esxcfg-vswitch -l
DVS Name                        Num Ports   Used Ports  Configured Ports  Uplinks
dvSwitch3-ISCSI-Storage 256                    7           256                      vmnic7,vmnic3
 
  DVPort ID           In Use      Client
  131                 1           vmnic3
  132                 1           vmnic7
  56                   1           vmk0
  57                   1           vmk1
  58                   1           vmk2
  59                   1           vmk3
 
 
 
6. Delete the VMkernel NICs that were created previously.

This is so we can add them back with an MTU of 9000, the GUI does not allow this. We also need a DV Port ID to create it via the service console.

/usr/sbin/esxcfg-vmknic -d -s dvSwitch3-ISCSI-Storage -v 56
/usr/sbin/esxcfg-vmknic -d -s dvSwitch3-ISCSI-Storage -v 57
/usr/sbin/esxcfg-vmknic -d -s dvSwitch3-ISCSI-Storage -v 58
/usr/sbin/esxcfg-vmknic -d -s dvSwitch3-ISCSI-Storage -v 59
 
 

7. Create VMKNICs with MTU 9000
Using the DV Port ID recorded previously we create the VMkernel port with an MTU of 9000 (for jumbo frames)
/usr/sbin/esxcfg-vmknic -a -i 10.1.1.50 -n 255.255.255.0 -m 9000 -s dvSwitch3-ISCSI-Storage -v 56

/usr/sbin/esxcfg-vmknic -a -i 10.1.1.51 -n 255.255.255.0 -m 9000 -s dvSwitch3-ISCSI-Storage -v 57

/usr/sbin/esxcfg-vmknic -a -i 10.1.1.52 -n 255.255.255.0 -m 9000 -s dvSwitch3-ISCSI-Storage -v 58

/usr/sbin/esxcfg-vmknic -a -i 10.1.1.53 -n 255.255.255.0 -m 9000 -s dvSwitch3-ISCSI-Storage -v 59 

8. Confirm the VMkernel NIC settings:

/usr/sbin/esxcfg-vmknic -l

Interface  Port Group/DVPort   IP Family IP Address                              Netmask         Broadcast       MAC Address       MTU     TSO MSS   Enabled Type
vmk0       56                 IPv4      10.1.1.50                            255.255.255.0 10.1.1.255    00:50:56:7b:02:8c 9000    65535     true    STATIC
vmk1       57                 IPv4      10.1.1.51                            255.255.255.0 10.1.1.255    00:50:56:77:09:82 9000    65535     true    STATIC
vmk2       58                 IPv4      10.1.1.52                            255.255.255.0 10.1.1.255    00:50:56:7c:6e:72 9000    65535     true    STATIC
vmk3       59                 IPv4      10.1.1.53                            255.255.255.0 10.1.1.255    00:50:56:7d:ef:7d 9000    65535     true    STATIC

 
 
9. Test that the VMkernel settings with an MTU of 9000 is working correctly:
/usr/sbin/vmkping -s 9000 10.1.1.200
PING 10.1.1.200 (10.1.1.200): 9000 data bytes
9008 bytes from 10.1.1.200: icmp_seq=0 ttl=255 time=0.533 ms
9008 bytes from 10.1.1.200: icmp_seq=1 ttl=255 time=0.501 ms
9008 bytes from 10.1.1.200: icmp_seq=2 ttl=255 time=0.518 ms

 
 
 
10. View SCSI adaptors and confirm the adaptor used for ISCSI
/usr/sbin/esxcfg-scsidevs -a
vmhba0  mpt2sas           link-n/a  sas.5a4badb00ecf3400                    (3:0.0) LSI Logic / Symbios Logic Dell PERC H200 Integrated
vmhba1  lpfc820           link-n/a  fc.20000000c996a8bd:10000000c996a8bd    (4:0.0) Emulex Corporation LPe12000 8Gb Fibre Channel Host Adapter
vmhba2  lpfc820           link-n/a  fc.20000000c99aed0c:10000000c99aed0c    (5:0.0) Emulex Corporation LPe12000 8Gb Fibre Channel Host Adapter
vmhba3  ata_piix          link-n/a  sata.vmhba3                             (0:31.2) Intel Corporation 2 port SATA IDE Controller (ICH9)
vmhba32 ata_piix          link-n/a  sata.vmhba32                            (0:31.2) Intel Corporation 2 port SATA IDE Controller (ICH9)
vmhba33 iscsi_vmk         link-n/a  iqn.1998-01.com.vmware:starscream-2d842e60() Software iSCSI

11. List VMKNICs bound to the ISCSI software adaptor
/usr/sbin/esxcli swiscsi nic list -d vmhba33
No iSCSI Nics Found
 
 
12. Bind VMKNICs to the software ISCSI adaptor
Allow more sessions per datastore, and allow MPIO multiplathing.
 
/usr/sbin/esxcli swiscsi nic add -n vmk0 -d vmhba33
Errors:
Add Nic failed in IMA.

This error will occur when there is more than 1 physical uplink on the switch the VMkernel NIC is connected to.

Changing the vSwitch temporarily so there is only one active adaptor and the rest to unused, will allow the VMK to be bound to the software ISCSI adaptor.

/usr/sbin/esxcli swiscsi nic add -n vmk0 -d vmhba33
/usr/sbin/esxcli swiscsi nic add -n vmk1 -d vmhba33
/usr/sbin/esxcli swiscsi nic add -n vmk2 -d vmhba33
/usr/sbin/esxcli swiscsi nic add -n vmk3 -d vmhba33
 

13. Confirm that all VMkernel NICs were sucessfully bounded to the ISCSI adaptor.
/usr/sbin/esxcli swiscsi nic list -d vmhba3

vmk0
    pNic name: vmnic3
    ipv4 address: 10.1.1.50
    ipv4 net mask: 255.255.255.0
    ipv6 addresses:
    mac address: b8:ac:6f:7f:ff:d8
    mtu: 9000
    toe: false
    tso: true
    tcp checksum: false
    vlan: true
    link connected: true
    ethernet speed: 1000
    packets received: 139011
    packets sent: 17613
    NIC driver: bnx2
    driver version: 1.6.9
    firmware version: 5.0.11 NCSI 2.0.5
 
vmk1
    pNic name: vmnic3
    ipv4 address: 10.1.1.51
    ipv4 net mask: 255.255.255.0
    ipv6 addresses:
    mac address: b8:ac:6f:7f:ff:d8
    mtu: 9000
    toe: false
    tso: true
    tcp checksum: false
    vlan: true
    link connected: true
    ethernet speed: 1000
    packets received: 139011
    packets sent: 17613
    NIC driver: bnx2
    driver version: 1.6.9
    firmware version: 5.0.11 NCSI 2.0.5
 
vmk2
    pNic name: vmnic3
    ipv4 address: 10.1.1.52
    ipv4 net mask: 255.255.255.0
    ipv6 addresses:
    mac address: b8:ac:6f:7f:ff:d8
    mtu: 9000
    toe: false
    tso: true
    tcp checksum: false
    vlan: true
    link connected: true
    ethernet speed: 1000
    packets received: 139011
    packets sent: 17613
    NIC driver: bnx2
    driver version: 1.6.9
    firmware version: 5.0.11 NCSI 2.0.5
 
vmk3
    pNic name: vmnic3
    ipv4 address: 10.1.1.53
    ipv4 net mask: 255.255.255.0
    ipv6 addresses:
    mac address: b8:ac:6f:7f:ff:d8
    mtu: 9000
    toe: false
    tso: true
    tcp checksum: false
    vlan: true
    link connected: true
    ethernet speed: 1000
    packets received: 139011
    packets sent: 17613
    NIC driver: bnx2
    driver version: 1.6.9
    firmware version: 5.0.11 NCSI 2.0.5

14. Now change back the vSwitch settings so that any unused uplink adaptors active again.

15. On the ESX server Click "Rescan..." under the Configuration tab "Storage adaptors" section.

16. On each VMFS volume Click "Properties" and then "Manage Paths"

17. You will now see multiple paths to the VMFS datastore (LUN).

18. Change the path selection to "Round Robin (VMware)"