You can use both ports for front-end FCP servers, but you will not be able to add any expansion shelves to your 2020 so you will be forever stuck with the 12 internal disks.
There are only 2 FC ports on the 2020 (as it's an entry level controller). Of course if you want to expand later, you could get an FC switch, then go back to using 1 port for FCP and one port for disk expansion.
If the LUNs are configured on node 1, and the ESX server getting those LUNs is connected to node 2, it will work as the partner can get access to the LUNs on node 1 through the cluster interconnect.
But the performance will be less since you are introducing an extra hop. Whether you notice the difference or not, I can't tell. But that is one way around the limit. You may be better off matching LUNs to the controller accessing those LUNs.
This AutoSupport has been generated because a lun mapping or igroup type misconfiguration has been detected. To troubleshoot this issue, issue a 'lun config_check' command. This command will list out the problems that generated this AutoSupport. The primary cause of this AutoSupport will be changes to the lun mapping configuration while the cluster interconnect is down and the safety mechanism have been overridden by the user using the various '-f' tags on commands like 'lun online','lun map' or 'igroup add'. The errors will typically include cases of having a lun on each filer mapped to the same logical unit number for the same initiator. In 'single_image' mode, you can have only one LUN N for each initiator across the cluster. This is enforced when the cluster interconnect is up. If the IC is down, lun map changes are prevented, unless you use the -f option. However, the -f option should be used with caution.
it's ok ? it's but a connect to the node 2 ? what I do ?
That's looks like the warning ONTAP gives when it detects that you are going down the non-optimized path through the interconnect. So you said the host connected to node 2 was accessing LUNs on node 1.
That will cause the ASUP to be generated to warn you about it. In your case, it's expected so I would have the GSC archive (i.e. close) the case.
I have not understood this passage : "hat will cause the ASUP to be generated to warn you about it. In your case, it's expected so I would have the GSC archive (i.e. close) the case" you advise me to put the second link on node 1?