After replicating your copa data source into bw side, you can cross check at Data source level.
go to your data source, double click on it, click on extraction tab, there see it.
Direct access - Allowed mean it will allow to create direct dtp other wise not possible.
Even by using ROOSOURCE table also you can check whether your data source supports direct access or not.
Go to ROOSOURCE table at ecc side, try to see the contents for your data source and observe field VIRTCUBE - 1, means it supports, if you have any other values then it won't support.
Normally direct access was used where there is less data extricting