I can not see HDD

Hi, not sure how to resolve your inability to see the HDD, but in case you haven’t seen it, here is an older short thread on using a hardware based RAID (which implies to not really use it, as BTRFS is essentially a SW RAID): BTRFS on Hardware RAID (LSI/Avago controller)

If you look on other forums about BTRFS discussions you will see similar sentiments, as BTRFS is not aware of an underlying HW RAID …