Azure SQL Database DTU

0
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I have multiple Azure SQL Databases and when I connect to them using SQL Server Management Studio, they all appear to be running on the same VM -- meaning, when I connect to the instance of SQL Server, I see my databases listed in Object Explorer.

With that said, should I assume that the DTU level set through the portal is only a throttling setting? In other words, should I assume that the databases are already running on a pretty powerful instance but based on DTU settings, Azure is throttling up/down allowed requests?

I don't think it would make a lot of sense for Microsoft to move a database to a new instance when the DTU level is increased.

2
sql-serverazureazure-sql-database
This is not really your question, but seeing the databases in your subscription under Object Explorer does not necessarily mean they are running on the same underlying hardware. Remember that with Azure SQL Database you have to stop thinking about that "thing" as a regular SQL Server instance, because that's not what it really is... – Aaron Bertrand
Thanks for the insight. I guess what made me think it was running on the same H/W is because I seem to be connecting to a VM. In the Server Name, I'm entering myazuredatabase.database.windows.net. – Sam
That's just a logical name for your subscription. – Aaron Bertrand
Right - there's no VM to speak of: you're connecting to a multi-tenant database service. DTU are assigned either to a specific database or a collection of databases (using an elastic pool). This has nothing to do with VM limitations. – David Makogon

2 Answers

3
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Yes, you are correct, DTU is not a VM total capacity, just a way to cap database performance.

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DTU is for individual databases, and can range from a small percentage of VM resources to the entire database taking one single machine. Azure doesn't guarantee all the databases under one server belongs to one physical sql server instance. The databases can potentially spread across multiple sql instances though they belongs to one logical server. For checks like firewall, it appears the instances cross connect to the master database and query the rules.