Hello,
Lets say we have a VM with hosted application and 99.9% SLA, and lets say we decide to deploy additional VM to host the same app, according to lectures this would increase our availability which seems logical, but my confusion is with compound SLA, if we calculate compound SLA for the same VM's then 99.9% x 99.9% = 99.8% , so how is the availability increased if the compound SLA is lower?
@Djordje-Petrovic , I hope all is well. Take a look at the following article, as it will help walk you through the concepts.. specifically look approx. 1/2 way down for the Understanding SLA's section
Using business metrics to design resilient Azure applications:
You are interested in the COMPOSITE SLA section.
Cheers,
Adam
Thank you @Adam-Gordon , this is a very useful article that I will take a look, also I passed the AZ 900 today thanks to IT Pro TV so everything is good now 
Thank you,
Regards