You don't have to give up cross DC replication if you do it asynchronously, but you lose cross shard consistency when there is a dirty fail over. This effects distributed transactions and series of single part transactions that depend on each other across different shards.
What Volt supports right now is actually asynchronous replication that does preserve cross shard consistency, but that is not going to last.
You can do synchronous multi-DC replication, but then you have Spanner and the associated latency of multiple data-center quorums.
What Volt supports right now is actually asynchronous replication that does preserve cross shard consistency, but that is not going to last.
You can do synchronous multi-DC replication, but then you have Spanner and the associated latency of multiple data-center quorums.
There is also Calvin http://bit.ly/RGW9RY