SQL Azure failover [closed]

Question

In case SQL Azure node fails, how does it work?

1. Do I lose any data? the latest committed data since the last backup/replication?
2. Is the data always replicated instantneously?

In the worst case scenario, what could happen to my committed data?

Cheers.

Answer 1

SQL Azure always keeps data in three replicas (a primary and two standby). The first standby copy is done synchronously (ie in the same transaction) and the second asynchronously. Uncommited data may be lost but your commited data is safe.

When a hardware error the first standby is brought online. New connections are made to the new online copy. According to this the failover is not transparent and may result in termination of your connection with a generic connection error (10053 or 40197).

Of course, if it may terminate, you have to assume it will terminate and your code will have to be prepared to retry failed transactions.