Avid will only read/write media in the default filepath for media. Most people consider that to be a good thing, but it does limit you in subdividing media. Some thoughts, though:
The path for local storage is always X:/Avid MediaFiles/MXF/1/, where ‘X:’ can be most any drive, but the ‘Avid MediaFiles’ folder needs to live on the root of the drive, not in a subfolder. But that last number can be most anything, as long as it is a number. Some people use that to label their media by shooting date or capture date. So for today, the folder would numbered 110704. Anything the Avid will create, however, will be put into a (newly created) folder ‘1’, unless that folder has more than 2500 files, in which case the Avid auto-creates ‘2’, etc.
A lot of people manually manage their mediafiles, by renaming the Mediafiles folder per project, and only activating the media for the current project. For example, you would have:
X:/Avid MediaFiles/MXF/1
X:/Avid MediaFiles Coke/MXF/1
X:/Avid MediaFiles Pepsi/MXF/1
X:/Avid MediaFiles Test/MXF/1
The only active set (that the application will see and be able to use) is the first one (without the project name added). If you rename that folder, you will hide it from the system. Then you may “un-rename” the Pepsi or Coke set, for example, so that becomes active.
Another option on Windows is to use the ‘subst’ command, which allows you to create virtual drives in folders.
You could also partition drives, but that’s a little more cumbersome.
Hope this helps.