Did you check if the ESXi 7 recognize the H310 controller?  Dell 12 Gen. are not certified for vSphere 7 and when looking into HCL for the H310 https://www.vmware.com/resources/compatibility/search.php?deviceCategory=io&details=1&partner=23,1_bpartner&keyword=h31&page=1&display_interval=10&sortColumn=Partner&sortOrder=Asc

i can see it only goes up to 6.5. For sure it will work also in 6.7 but with 7.0 VMware only have the new native driver format and not the old vmklinux any more. So most likely your Host doesnt have a driver for the controller right now.

Regards,
Joerg

Hi Joerg,

Yes, the issue was the latest ESXi version wasn't supported. After installing 6.5.0 Update 2 (Build 13635690), my disks now show up.

You can also update to 6.5u3 or 6.5.latest and IIRC you can also install 6.7.latest even if its not supportet on paper.

Regards,
Joerg

I know this thread is older, but just in case you didn't find your final answer, or somebody else comes along and finds this looking for the same answer like I did because they can't get hold of ESxi 6.5 any longer:

The issue is only with the PERC H310 Mini controller.  Hop on eBay and pick up a H710 for cheap instead, and you'll be golden once it's installed. 

Beware: if you already had an array working under the H310, you'll effectively be wiping everything out and starting from scratch with your drives, so be sure you backup any critical data BEFORE attempting to upgrade to ESXI7.