SQL Azure failover / backup strategy for web app

Question

I'm building a web app using Azure & SQL Azure. I'm setting it up so each organization has their own database. Low to moderate traffic per customer organization.

I'm thinking about using SQL Azure Data Sync as part of a failover/backup plan, so that if SQL Azure goes down, my app can switch over to my on-premises SQL Server (read-only mode).

I would also be able to do all of my backups on-prem, instead of in the cloud which could incur costs.

• One issue may be trying to data-sync multiple databases to my on-prem sql server (not sure what the limit is on the number of databases that can be synced to one server)

• Bandwidth may be an issue, but I'll probably only sync daily.

Does anyone see any other problems with this approach?

Answer 1

Data Sync is ok, but may or may not be good for your particular DR plan since it's not a transactional sync model.

One option to consider is making a database copy:

CREATE DATABASE destination_database_name
    AS COPY OF [source_server_name.]source_database_name

Then you can create a backup from this copy, store the backup in blob storage, and (optionally) delete the database copy. While this does add an additional cost due to a second database being live, you can keep that cost to a minimum if you delete the database instance after creating a backup and storing to blob storage (remember that databases are amortized daily).

Since your backups would then be in blob storage, you could keep multiple backups in blob storage, and pull a backup to your on-premises server if needed.