The new license model of 8.1 avoid the VSC plugin to add a storage control if some license is "ENABLED" but the related options is set to off. In my case a multistore "ENABLED" license caused the "unable to add storage controller" message and in the kamino.log file there was reported the cause. This because multistore in in some way something manageable by VSC. I think this issue can be presente for NFS also if NFS is licensed. No issues seem to be present for FCP
Setting this to on solved the problem
options licensed_feature.multistore.enable on
2012-01-30 15:56:14,079 (Thread-56) ERROR [FilerUtil] - Failed to get vfiler info Api vfiler-list-info either requires license for multistore or requires the option licensed_feature.multistore.enable to be turned on (errno=13008)
netapp.manage.NaAPIFailedException: Api vfiler-list-info either requires license for multistore or requires the option licensed_feature.multistore.enable to be turned on (errno=13008)
Thank you for posting this, I was troubleshooting the output of 'smvi discover datastores' when setting up VSC 2.1.2 when I found a similar error in the SMVI server logs. The fix listed above addressed the problem for me as well.