You can mark storage devices, which are not properly detected, as local flash devices.
When you configure vSAN or set up a virtual flash resource, your storage environment must include local flash devices.
However, ESXi might not recognize certain storage devices as flash devices when their vendors do not support automatic flash device detection. In other cases, certain devices might not be detected as local, and ESXi marks them as remote. When devices are not recognized as the local flash devices, they are excluded from the list of devices offered for vSAN or virtual flash resource. Marking these devices as local flash makes them available for vSAN and virtual flash resource.