vmware and load balancing NFS trunks

Straight from the post below, this is the best way (currently) to load balance your NFS datastores…  No MPIO magic here unfortunately.


Basically you can setup IP alias on the NFS side and then setup multiple connections (using a unique IP) per datastore  on each ESX host. This works well if you are using a team of nics running IP-hash load balancing…

Static EtherChannel.

My setup is as follows:

ESXi 4.0 U1, Cisco 3750 Switches, and NetApp NFS on the storage side.

I have a total of 8 nics. I divided the nics into 3 groups.

2 nics on vSwitch0 for Mgmt & vMotion
3 nics on vSwitch1 for VM’s (Multiple port groups (3 VLANS))
3 nics on vSwitch2 for IP Storage (Mostly NFS, a little iSCSI)
(One vSwitch3 I also have a VM port group for iSCSI access from within the VM)

Since I have 3 nics on my IPStorage port group I needed a way to be able to utilize all three nics and not have the server just use one for ingress and egress traffic. This was done by:

Setting up a static EtherChannel on the cisco switch (Port Channel).
Configuring the cisco switch to IP Hash
Configure the vSwitch to “Route based on IP Hash” as well.

The next part is to create multiple datastores on the NFS device. Each of my NFS datastores is about 500GB in size. Reason for this is that my larger luns are iSCSI and are access directly from the VM using the MS iSCSI initiator from the VM itself.
My NetApp NAS has an address of, let say, So all my data stores are accessible by utilizing the address of “\\\NFS-Store#”. This will not be useful as the esx box and the cisco switch will always use the same nic/port to access the nas device. This is due to the algorithm (IP HASH) to decide what link it’ll go over. So to resolve the issue, I added IP aliases to the NFS box. NetApp allows to have multiple Ip addresses pointing to the same NFS export, I suspect EMC would do the same. So, I added 2 aliases 51 & 52. Now my NFS datastores are accessible by using Ip address,.51, & .52.

So I went ahead and added the datastores to the ESX box using the multiple IP addresses:

Datastore1 = \\\NFS-Store1
Datastore2 = \\\NFS-Store2
Datastore3 = \\\NFS-Store3

If you have more datastores it’ll just repeat: Datastore4 = \\\NFS-Store4 and so on…

Since having multiple datastores and address to each, the 3 nics on the ESX box dedicated to IP Storage get utilized. It does not aggregate the bandwidth but it does use all three to send and recieve packets. So the fastest speed you will get is 1Gbit, theoretically, each way for traffic but, it is better than trying to cram all the traffic over 1 nic.

I also enabled Jumbo Frames on the vSwitch as well as the vmNic for IP-Stroage. (need the best performance!)
I should mention that your NFS storage device should have EtherChannel setup on it as well. Otherwise, you’ll be on the same boat just on the other end of it.

Hope it helps!

Larry B.

I should mention that you should not use different addresses to access the same NFS share (datastore). It is not supported and may cause you issues.

2 thoughts on “vmware and load balancing NFS trunks

  1. Im thinking of trying this on my Nexenta box, however, we have ProCurve switches. Can I just TRUNK it. I understand vmware doesn’t do LACP yet….

  2. Keeping the current setup with 3NICs for storage in mind….

    Did you get a chance to look @ adding more VMKernel interface with additiona IP on the same network… to access NFS datastores; which might increase the bandwidth/speed to more than 1G ?

    I am not sure if we have the option to do that :)

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