E2740 - iSCSI mapping in a virtual environment

[jochen352]

Hello,

we have a NetApp E2740 with a dual iSCSI controller to provide additional storage for individual virtual machines. The iSCSI volumes should be mapped directly in the VMs. The VMs have two logical network adapters, one for the productive network and one for the iSCSI connection. The connection of host systems to the E2740 is not provided.

STORAGE:
C1/Ch3: 192.168.0.13
C1/Ch4: 192.168.0.14
C2/Ch3: 192.168.0.23
C2/Ch4: 192.168.0.24

VM (example)
NIC1: 142.32.10.103
NIC2: 192.168.0.103

The usual scenarios with two NICs and MPIO do not make much sense in this configuration, because they are only virtual NICs behind a vSwitch (teaming).

What configuration would be useful in this environment?

Best regards
Jochen

[kkemnitz]

You will still want to install the MPIO component (DSM), as the Windows virtual machine will still see multiple devices for the same disk even though only a single virtual NIC is being defined as a hardware component for the VM. Without the MPIO/DSM component, you will see something like this:

After installing the MPIO component, those paths will be combined into a single disk.

Hope this helps!

[kkemnitz]

Let me attempt to explain the necessary configuration a little bit better, based on an environment I have set up.

STORAGE iSCSI IP ADDRESES:

C1/Ch3: 192.19.21.111
C1/Ch4: 192.19.22.111
C2/Ch3: 192.19.21.112
C2/Ch4: 192.19.22.112

HOST:

vSwitch: iSCSI

VMkernel Adapters:
vmk7: 192.19.21.1
vmk8: 192.19.22.1

iSCSI Software Initiator Sessions:
192.19.21.1 -> 192.19.21.111 (vmk7 to C1/Ch3)
192.19.21.1 -> 192.19.21.112 (vmk7 to C2/Ch3)
192.19.22.1 -> 192.19.22.111 (vmk8 to C1/Ch4)
192.19.22.1 -> 192.19.22.112 (vmk8 to C2/Ch4)

VIRTUAL MACHINE

NIC2: Single NIC attached to iSCSI vSwitch, but provided two IP addresses: 192.19.21.205 and 192.19.22.205

iSCSI Software Initiator Sessions: 
192.19.21.205 -> 192.19.21.111 (To C1/Ch3)
192.19.21.205 -> 192.19.21.112 (To C2/Ch3)
192.19.22.205 -> 192.19.22.111 (To C1/Ch4)
192.19.22.205 -> 192.19.22.112 (To C2/Ch4)

Because there are 4 paths to the storage array initiated from the VM, regardless of how many vNICs have been defined, you will see multiple "unvirtualized" disk devices for the same volume presented from the storage array. Installation of E-Series DSM will "virtualize" those paths into a single disk.

Hopefully this is a better explanation than my first reply.