It may be the case that your CL is the issue. You are writing it at
ONE, which means that out of the 4 replicas of that key (two in each
data center), you are only putting it on one of them.
cassandra will always try to replicate key to all available replicas.
Under normal conditions if you do write + wait about 1 sec + then read
at CL.ONE you should get back correct value. Consistency in cassandra is
not problem in real world, its way better then SQL databases with async
replication. Make sure you have your clients clock synced via NTP,
