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vSAN 6.6 Config Assist incorrectly reports Physical NIC warning with LACP/LAG

A very short post simply to bring an issue to your attention which a number of folks have pinged me about this week. With vSAN 6.6, there is a new feature called Configuration Assistant. As the name implies, it tries to highlight possible configuration issues with your vSAN infrastructure. A number of these checks are related to network configuration. Configuration Assistant checks to make sure that the vSAN network has availability by verifying that there are 2 or more physical NICs. For example, let me show you my setup. Here is my vSAN vmkernel port, and as you can see, it has two physical NICs/two uplinks (vmnic0 and vmnic1):

Now if I check the Configuration Assistant – Physical NICs test, I see that it is all green/passes the test:

OK – that works fine. However, we made a little oversight when it comes to LACP/Link Aggregation and the use of LAGs (Link Aggregation Groups). A LAG can contain multiple physical NICs. However, the LAG group then gets added/associated with a single uplink (e.g. vmnic0). Now when the vSAN vmkernel port is using a LAG, it is only using one uplink, but within that single uplink, the LAG can contain multiple physical NICs. Now the Configuration Assistant will report a warning “Portgroup only has 1 active physical NIC”, as shown in the following screenshot:

This is obviously incorrect, and the test is looking at uplinks rather than physical NICs. The bottom line is that we are aware of the issue, and if you have a LAG configured for the vSAN network, you can safely ignore this warning in Configuration Assistant. We are working on a solution.

Before finishing, I’d like to take an opportunity to point you to our new vSAN Network Design Guide, which has lots of good information around LACP, LAG and many other network considerations for vSAN. Please check it out. You can download it as a PDF for your reference. Feedback always welcomed.

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