Many thanks so far!
In fact I have a little knowledge about partitions but it is insufficient about the relation of Extended Partitions / Primary Partitions and Logical Drives. (In fact people never speak about it!
a) What are the conditions for creating Logical Drives? Can a Logical Drive be set for any partition type? I rather guess you need Extended Part. to set up Logical Drives.
b) Are there different types of Extended Partitions? How many Extended Partitions can you have on one drive? Can you delimit their size or do they take the rest of the disk?
c) Would the following setting be possible: Disk with 3 Primary Part. :
1 Windows NTFS
1 Extended with Log. Drives (name them A - D)
1 Extended with Log. Drives (name them E - H)