I am wonder why after creating a very simple DataTable and then setting it to null why Garbage Collection does not clear out all the memory used by that DataTable. Here is an example. The variable Before should be equal to Removed but it is not.

{
 long Before = 0, After = 0, Removed = 0, Collected = 0;

 Before = GC.GetTotalMemory(true);
 DataTable dt = GetSomeDataTableFromSql();
 After = GC.GetTotalMemory(true);
 dt = null;
 Removed = GC.GetTotalMemory(true);
 GC.Collect();
 Collected = GC.GetTotalMemory(true);
}

Gives the following results.

Before = 388116
After = 731248
Removed = 530176
Collected = 530176