New Azure SQL Database Services, how scalable and what are DTUs

Question

The new new Azure SQL Database Services look good. However I am trying to work out how scalable they really are.

So, for example, assume a 200 concurrent user system.

For Standard

Workgroup and cloud applications with "multiple" concurrent transactions

For Premium

Mission-critical, high transactional volume with "many" concurrent users

What does "Multiple" and "Many" mean?

Also Standard/S1 offers 15 DTUs while Standard/S2 offers 50 DTUs. What does this mean?

Going back to my 200 user example, what option should I be going for?

Azure SQL Database Link

Thanks

EDIT

Useful page on definitions

However what is "max sessions"? Is this the number of concurrent connections?

Answer 1

There are some great MSDN articles on Azure SQL Database, this one in particular has a great starting point for DTUs. http://msdn.microsoft.com/en-us/library/azure/dn741336.aspx and http://channel9.msdn.com/Series/Windows-Azure-Storage-SQL-Database-Tutorials/Scott-Klein-Video-02

In short, it's a way to understand the resources powering each performance level. One of the things we know when talking with Azure SQL Database customers, is that they are a varied group. Some are most comfortable with the most absolute details, cores, memory, IOPS - and others are after a much more summarized level of information. There is no one-size fits all. DTU is meant for this later group.

Regardless, one of the benefits of the cloud is that it's easy to start with one service tier and performance level and iterate. In Azure SQL Database specifically you can change the performance level while you're application is up. During the change there is typically less than a second of elapsed time when DB connections are dropped. The internal workflow in our service for moving a DB from service tier/performance level follows the same pattern as the workflow for failing over nodes in our data centers. And nodes failing over happens all the time independent of service tier changes. In other words, you shouldn’t notice any difference in this regard relative to your past experience.

If DTU's aren't your thing, we also have a more detailed benchmark workload that may appeal. http://msdn.microsoft.com/en-us/library/azure/dn741327.aspx

Thanks Guy