Although I have written an entire book about Max-Hellmuth Ostermann (will be published next year), I have never come across anything which would indicate that any of his ancestors were nobles.
You ask if Ostermann is a common name. Well, try googling Ostermann and you'll get over one million (+
1 100 000) hits.
I tried Dikov and got "only"
35 600 hits. However, Bergström is even worse:
2 180 000 hits!
