Now larger meshes also work.
Now i read that there is also a thing called buffers with indexed arrays. If i understand it correctly i do not need to feed all the vertexes even double but only the unique ones and pass indices to them. So like i do in gld3ds where i have a list of vertexes and a list containing indices to them.

so i need two vbo's one for the vertexes and one for the indices.

but how are these combined? Simple example anyone?