When flash devices are not automatically identified as flash by ESXi hosts, you can manually mark them as local flash devices.
Flash devices might not be recognized as flash when they are enabled for RAID 0 mode rather than passthrough mode. When devices are not recognized as local flash, they are excluded from the list of devices offered for vSAN and you cannot use them in the vSAN cluster. Marking these devices as local flash makes them available to vSAN.
Prerequisites
- Verify that the device is local to your host.
- Verify that the device is not in use.
- Make sure that the virtual machines accessing the device are powered off and the datastore is unmounted.