vSAN Multiple VMKs for multipath not functioning?

[dmetcalfe92]

Hi,

I recently re-did all the network cables for my lab at home, and since that, my vSAN was performing abnormally.

I'm currently running vCenter 6.0.0 build 3339084, ESXi 6.0 build 3380124

I looked at the resyncing components, and found 300GB resyncing, with a 3 day ETA.

Looking in the performance charts of the hosts, I noticed it was only using one NIC, and the speed was between 5000-8000 KBps.

Then I checked the NIC speeds, and sure enough, the NIC it was using to resync was only performing at 100mbps (faulty port on switch)

I've configured 2x vSAN VMK's each on their own vLAN, and each with their own dedicated NIC on the DVS. All the network connectivity tests pass which indicates it CAN use both NICs & both VMKs I've provisioned:

So I shutdown the 100mb port on my switch, and it switched over to the other VMK, performing at gigabit speeds!

What concerns me here is that it chose to use only one NIC, and it picked the slower of the two.

I'm not bothered about it picking the slower of the two as I've resolved this fault (although this should be a concern for prod environments), I'm bothered about the fact it doens't use both NICs at once.

I've done some googling and can't find much on the internet. Although at the very bottom of this page (http://vtricks.com/working-with-vsan-part-iv), he is describing the same fault as me, he can't get both VMKs to function again

This was 11 months ago so I would assume if it's a bug, it should've been fixed? Unless it's an unknown bug that's been lurking about for some time?

Has anyone else experienced the same issues I have? I'm unsure if it's something I have misconfigured somewhere.

[dmetcalfe92]

I've done some more tests, unplugging each nic individually, (vmnic1 & vmnic2). I waited for the other NIC to start being utilised before plugging back in.

Ignore where vmnic1 has slow utilisaiton (was 100mb port).

It just doesn't utilise both NICs at once for some reason, it's working in a sort of failover fashion, but I'd like to utilise both NICs at once.

In this example, at 11:10, both vmnics were plugged in but it was only utilising one:

[zdickinson]

Good morning, this is as expected.  With two NICs, even when both are active, only one will be utilized.  It is for fail over only.  You need a third party multi-pathing software to do this.

A possible option has been discussed where you make two vSAN vSwitches.  One with NIC_A as active with NIC_B as standby and then one with NIC_B as active and NIC_A as standby.  This may allow both NICs to take on traffic.  I can verify that it works with vMotion traffic.

Thank you, Zach.

[dmetcalfe92]

Hi Zach,

Thanks for your response. At the moment the ports are configured as access ports with only access to the specific VLAN they need.

In the scenario you describe, they would have to be trunk to allow standby adapter utilisation on both vSwitches.

I'll have a play and configure 2x new switches as you describe and change the ports to trunk.

Would you recommend using a DVS or standard vSwitch?

Thanks again

[zdickinson]

I think VDS vs standard is based on your scale.  We did VDS initially on our 3 host cluster, but then moved to standard.  It just wasn't worth the complexity.  Thank you, Zach.