Windows 7 hdd not searchable

Hello,
I'm using Windows 7 Home Premium 64 bit.
I have 4 internal independent harddrives. Whenever I search for something, one of these hdd's, D, is omitted from the search. I opened up disc management, and noticed that D is dynamic, while all the others are basic.
What's the difference between basic and dynamic? It looks like you can make a basic disc dynamic, but not vice versa.
Is there a way to make D searchable? I like to search all the hdd's at once from the start menu.

Thank you in advance!