Last week after I added a new host to a vSAN Cluster, the following vSAN health alarm appeared:
This was a new host, a fresh installation, so the first thing I did was to check the firmware drivers and make sure that it is is using the same versions as the other hosts in the cluster. The host was running the same ESXi version and had the same firmware and drivers installed.
While troubleshooting and searching I found this KB which states that the issue is because that vSAN Health Service is not able to find the appropriate controller utility for the storage controller and that you need to install the controller utility.
This was a bit strange, as the host was just installed, so I checked that the controller utility was missing running /opt/lsi/perccli/perccli show.
To fix the issue you have to download and install the controller utility from the vendor portal (DELL, HP). So, I went on DELL site, downloaded and installed VMware PERCCLI Utility For All Dell HBA/PERC Controller and the alarm was gone.
After you install the controller when you run /opt/lsi/perccli/perccli show you should get something like that: