Re: Unable to connect via cqlsh or datastax-driver
as it turned out, the problem was that our secondary DC was indeed overloaded and therefore dropped read requests which where executed during connection establishment.
The cause of this overload might be interesting: Actually we ran reversed values for dclocal_read_repair_chance and read_repair_chance. dc_local_read_repair_chance had to be 0.1 and read_repair_chance 0.0, but it was otherwise round. Obviously this was no problem until we setup the second DC.