Questions around iSCSI storage for vSphere

[Mohammad1982]

Hi All,

Here is the scenario,

I have configured a virtual switch with only one port and then attached 4 vmnics (all active and teamed) to the vswitch. After this I created a vmkernel port and named it iSCSI and then assigned a IP address to it which is in the same subnet as the storage array. Then I enabled the iSCSI software initiator and used dynamic discovery to discover the target and then did a rescan and wow I can see the LUN.

My question is, to achieve multipathing we need to bind the software iSCSI adapter to the vmnic. If I am not binding the software iSCSI adapter then from which vmnic it is seeing the storage. I am not able to understand how is it seeing the storage.

What if I used etherchannel  and use all 4 vmnics of 1 Gb to make a pipe of 4 GB. Will I get the 4 GB bandwidth, how about multipathing in this case,

Please help.

[vmroyale]

Hello.

Note: This discussion was moved from the VMware Go and VMware Go Pro community to the VMware vSphere Storage community.

Good Luck!

[rickardnobel]

Mohammad Wasimuddin wrote:

My question is, to achieve multipathing we need to bind the software iSCSI adapter to the vmnic. If I am not binding the software iSCSI adapter then from which vmnic it is seeing the storage.

If not binding the iSCSI Vmhba to any particular vmnic then it would depend on the Load Balancing Policy you have selected for the four cards, but in practise it would be just any one of them that you see the storage through.

What if I used etherchannel  and use all 4 vmnics of 1 Gb to make a pipe of 4 GB. Will I get the 4 GB bandwidth,

No, unfortunately you will not. Since the "IP Hash" (Vmware name of Cisco Etherchannel) will use a hash of the IP Source and the IP Destination you will always travel through one of the VMNICs and you will always only get 1 GBit/s no matter how many VMnics you put into the team.

[Mohammad1982]

But in case of VMNetwork port group of virtual machines when configured for Etherchannel load balances accross all the vmnics right?  Even if I have one virtual machine with one IP address.

Now the Etherchannel is configured on the cisco switches and then etherchannel(vifs netAPP) is also configured on the netapp storage.

4  1Gb  nics are bound to make one 4 Gb pipe. Will it load balance??

[rickardnobel]

Mohammad Wasimuddin wrote:

But in case of VMNetwork port group of virtual machines when configured for Etherchannel load balances accross all the vmnics right?  Even if I have one virtual machine with one IP address.

If you have a Port Groups for virtual machines and the VMNICs are configured for "IP Hash" then you will have a loadbalancing across the physical nics. However, each virtual machine will always travel over only one physical VMNIC, that is: a virtual machine could never get more than 1 Gbit/s, but with a bit of luck your different VMs will spread across all VMNICs (however this is not certain).

Now the Etherchannel is configured on the cisco switches and then etherchannel(vifs netAPP) is also configured on the netapp storage.

4  1Gb  nics are bound to make one 4 Gb pipe. Will it load balance??

The load balancing is always done from the sending side of a Etherchannel (802.3ad) and in your case the Netapp will decide how/if it will load balance, and then your Cisco switch will decide how to load balance up to your Host. The only certain thing here is how the ESX/ESXi host will do the outbound load balance and that will be that all traffic from one IP address on the Vmkernel to one IP address on the iSCSI target will always travel across one physical VMNIC.