Can Google Cloud SQL perform automatic instance failover across zones?

Question

According to documentation, data of Cloud SQL is replicated across multiple zones. But this can only prevent data loss in the event of zone outage. In order to ensure high availability of the service, does Cloud SQL offer cross-zone DB instance failover capability similar to Amazon RDS?

Answer 1

All Cloud SQL data is replicated in multiple zones. If there is a zone outage then the instance fails over to another, available, zone automatically.

See https://developers.google.com/cloud-sql/faq#replication

Answer 2

Failover is automatic and mostly transparent to the client, all database clients need to do is reconnect when the connection is lost https://cloud.google.com/sql/docs/mysql/high-availability

This is not what many 'Enterprise' databases would consider high availability, Products such as Oracle RAC with hot/hot or master/master setups would failover transparently and clients would not notice that an instance had died, the application would keep on running without any outage.

With CloudSQL your failover instance is cold and gets started up after Google has noticed your primary instance has stopped responding for an minute. So there is still an outage for a few minutes. The main advantage is the replication, if a disaster takes out the whole zone you can be up and running on another zone in a few minutes.