I have ported a MySQL-based ActiveRecord Rails app that was somewhat complicated to Postgres, and then on to CockroachDB. It works pretty well, so I'd give it a go. We're also committed to supporting ActiveRecord via the Postgres connector, so if you run into any bugs, we would do our best to fix them. I am personally invested in ActiveRecord support myself. At this point ORM support on CockroachDB is driven mostly by usage so please try it!
Your other questions are better answered on the blog post, but quickly:
* CockroachDB core comes with a `dump` command to backup your databases. CockroachDB Enterprise has blazingly fast _incremental_ cloud backup and restore, the kind that you might want for a very large deployment.
* Replication is managed under the hood by sharding the data into many ranges that are each 64mb in size. Each range is replicated using Raft, and if a node goes down, the other replicas scattered across the cluster seamlessly take over and upreplicate a new replica to "heal" the cluster.
* The horizontal scaling is indeed plug and play - just add more nodes to the cluster and they'll automatically rebalance replicas across the cluster with no downtime and no additional configuration.
Your other questions are better answered on the blog post, but quickly:
* CockroachDB core comes with a `dump` command to backup your databases. CockroachDB Enterprise has blazingly fast _incremental_ cloud backup and restore, the kind that you might want for a very large deployment.
* Replication is managed under the hood by sharding the data into many ranges that are each 64mb in size. Each range is replicated using Raft, and if a node goes down, the other replicas scattered across the cluster seamlessly take over and upreplicate a new replica to "heal" the cluster.
* The horizontal scaling is indeed plug and play - just add more nodes to the cluster and they'll automatically rebalance replicas across the cluster with no downtime and no additional configuration.