The Microsoft Azure cloud platform offers a vast array of services including cloud storage. Within Azure storage, there are multiple offerings but the most economical is blob object storage. The very large and growing Azure service offerings make for a complicated charging model. This posting attempts to explain the pricing model for Azure blob storage.
Blob storage is available in two storage tiers: hot and cool. You might think that hot has higher performance than cool but this is not correct – they have similar data throughput and data access times. If you have enough Internet bandwidth, the performance is amazing whether you are using hot or cool. The biggest difference between the tiers is the cost model and there is also a small difference in the availability provided in the Azure Service Level Agreement. For most archival applications, the cool tier is the way to go as this will result in lower costs.
Microsoft has a global network of data centers and the cost structure is affected by the location that you choose. There is a good selection of lower cost locations in North America and Europe including East US 2, Central US, South Central US, West US 2, West Central, Canada East, Canada Central, North Europe and West Europe.
An additional important factor affecting cost is the level of redundancy selected. The main options are:
As you would expect, LRS is the lowest cost redundancy option.
Having selected the storage tier, the Azure region and the level of redundancy, the monthly cost depends on several components:
If you choose the cool storage tier, one of the lower cost regions and LRS redundancy, blob storage account costs are calculated as below.
As an example, I will take an average capacity of 100 TB held in the cloud, 5 TB uploaded and 5 TB downloaded during the month. In this case, the cost will be broken down as shown below.
|Cost Component||Cost / Month|
|Capacity (100 TB)||$1,000|
|Uploads in month (5 TB)||$15|
|Downloads in month (5 TB):|
|>> Data Retrieval Cost||$50|
|>> Download Bandwidth Cost||$435|
In addition, there will be a relatively small charge for the operations component.
Azure has a complicated charging structure because it offers such a wide range of services. But for anyone looking to implement hybrid Azure blob storage with transfers between local storage and the cloud, I hope that this posting demystifies the cost model.