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The Cost of Azure SQL Database


[This is part Ten of Top 10 Things You Will Hate About Azure SQL Database]


If Microsoft is good at nothing else they are geniuses when it comes to creating complicated licensing and billing. They have decided to apply their talents to the billing for Azure SQL database. I realize that they have done their homework and the market will probably support the pricing tiers they created, but they also created a change in how new customers will decide to apply SQL Database. The biggest change is that you used to pay for the amount of data you were storing and now you a pay a set fee per database. You decide how much you want to pay based less on the amount of data and more on the performance you hope to get.

Currently there are three Service Tiers to choose from: Basic, Standard, and Premium. (Until September of 2015 you can also choose Web and Business, but if you are just now diving into ASD you can safely ignore these.) Within the Standard and Premium tiers there are various performance levels (S0, S1, S2, P1, P2, and P3). The tiers and performance levels get steadily faster and expensive as you go. The Basic tier lives up to its name and isn’t really intended for production level applications. It has most of the features of the higher tiers and the same uptime (99.99%), but it only has a DTU = 5 and an BTR = 17,805/hour. If you are like most DBA’s, at this point you are wondering what in the world is a DTU?

DTU stands for Database Throughput Unit and BTR is the Benchmark Transaction Rate. Microsoft knew that they couldn’t just tell DBA’s that Basic is fast, Standard is faster and Premium is fastest so they created a measurement to allow for comparing the various performance levels. A DTU is a measurement combining CPU, memory, physical reads, and transaction log writes. It is multiplicative, meaning 50 DTU’s performs about five times as well as 5 DTU’s. The transaction rate is based on a standard benchmark used by Microsoft and gives an approximation of what you can expect as your throughput for each level. There is an undeniable marketing feel to this approach, but it does give a basis for comparison.

  Basic Standard Premium

Database   size limit

2   GB

250   GB

500   GB

Self-service   restore

Any   point within 7 days

Any   point within 14 days

Any   point within 35 days

Performance   objectives

Transaction   rate per hour

Transaction   rate per minute

Transaction   rate per second

Database   throughput units**

Basic:   5

S0:  10

S1:  20

S2:  50

P1:  100

P2:  200

P3:  800

Performance   levels and monthly pricing

Basic:  $4.99

 S0:  $15

 S1:  $30

 S2:  $75

  P1:  $465

  P2:  $930

     P3:  $3,720

(Taken from the Microsoft Azure Blog on 8/26/2014 when these prices were first announced.)
As you can see the highest level Premium/P3 is significantly higher in expected performance than a Basic database. You can expect to pay for that difference. The higher levels allow for ASD to be used for an enterprise level application, but the cost as of this writing is about $5/hour (the smallest billing unit is currently a day, but Microsoft will be adding hourly billing as of November 1, 2014). Quite a bit when you contrast with the $.16/day that you pay for the Basic level. The good news is that it is easy to change the service level. You can start out with a Basic database and upgrade to Standard or Premium when you are ready to deploy. You can modify the level once you have a baseline for what is needed and even change it based on seasonal activity to keep costs down. Changing the level is fairly simple in the Azure Management Portal or can be scripted PowerShell.

I’ve grown more accustomed to the new tiers, but when they first came out they were a bit of a mind shift. Then again with Azure you have to expect things to change (see reason #4 to Hate Azure SQL Database). These pricing tiers have been in Preview since April of 2014 and they will be generally available starting sometime this month (Sept 2014). Microsoft has already adjusted these once since they first announced them based on feedback and they are talking about new solutions for having a large number of small databases that will hopefully be in place sometime next year. It will be iinteresting to see how this grows and to try to keep up with the pricing and usability structure – much like it was when I was first learning licensing for SQL Server.



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