Updated my mac with High Sierra yesterday, with success. Since I am new with mac OS and partition, I created one small (22GB) and one big partition (100GB). After a painstaking HS installation (on smaller partition of internal drive), I made a mistake of erasing my big partition one after copied everything on an external drive. Now I am stuck with how to get the multiple internal hard drive back. Pls help.. Only HS1 appears under internal tab. Thanks folks!