Would it be possible to deploy crdb in a active hot stanby scenario using 2 data centers? It can be any number of nodes but only 2 data centers. Traffic will always be consumed via one datacenter and will fall over to other if first dc is unhealthy. So strong consistency in the dc and eventual between. This is the local quorum cassandra concept which is what we are currently using.
If I understand correctly quorum will always be lost if using 2 datacenters so one wont be able to work without the other and would need atleast 3 dc with the correct locallity tags.
One way I can think of is to use the incremental backup restore functionality and do that automatically every few minutes. Some transactions will be lost but for this scenario its ok it can be handled.
To add an extra dc is not always possible because most of our clients run there own (banks).