Azure China is not a standard Azure Platform. There are a lot of small differences that might bring confusion to the customer. One of those differences is that there are no such things as Reserved Instances in Azure China.
They propose a different system called CPP. It stands for Compute Pre-Purchase. Let’s see how it differ from RI, and what are the pros and cons.
CPP Subscription
Azure CPP has to be subscribed via your Azure China Reseller (21 Vianet). You can not subscribe directly on the Azure portal. As opposed to the RI, it requires a pre-payment. Meaning that you will have to pay for the full period day 1. The duration for which you will subscribe has to be at least 7 months, and the end date must match with your contract anniversary date.
CPPs are taken for a specific template. For example Virtual Machine A-Series – A4 – CN. There is no conversion possible. It will apply only to the A4 Server in the region CN. With RI, you have much more flexibility inside and the reservation will apply automatically to any available VM in the flexibility group.
RI Can be refunded up to 50k$ on a rolling year with a 10% penalty. This is not the case for CPP.
CPP Application
This is a key point that makes CPP cool actually. As you probably already know, RIs are applied hourly. it requires that for each hour of billing, you have enough consumption to cover all your RI.
CPPs are different. They applied hourly. It means that for CPP, haveing 744 servers up during 1 hour is the same thing as having 1 server up all the time. At the end of the month, Azure China will tell how many hours you spent on each product, end CPP will be applied for the first hours. The rest of the costs will be paid at the on-demand rate.
It means that you can cumulate scheduling and CPP, which is not possible with RI.
CPP Impact
CPP Impact really depend on the type of server on which it apply. It goes from 20% up to 74%. But what we can say is that CPP Impact is generally higher than RI impact. It’s more comparable to a 3 year RI, even if you take your CPP only for a 7 month period. The duration of the CPP don’t have any impact on the percentage of rebate that you get.
Also, one cool thing is that there are CPP on all kind of server, even on A type server, on which you can not take any RI.
Conclusion
As a conclusion, we can say that on a finance perspective, CPP is way more efficient than RI, because it propose higher rebates on short duration, and because it applied monthly, so you can use CPP even on scheduled resources. But it’s not as flexible as Reserved instance, and it require a higher commitment with a good visibility and predictability of your infrastructure.
