We no longer wanted to keep in-house terabytes of event journals from various applications. We have already been using Azure services, so moving our data from rusty MongoDB collections to Azure storage was a natural step. But should we keep using MongoDB API offered by CosmosDB? Or go over to its SQL API? Or maybe Table/Blob storage would be sufficient for our needs? In this talk we will share our decision factors, what choice we made, how much it cost and how it performs. You will also see the implementation details in C#.