Microsoft recently announced the general availability of Cool Blob Storage in Azure, a new more affordable way to archive files in the cloud. In this post, I’ll explain what Cool Storage is, what Hot Storage is, how they are priced, how to deploy Cool Storage, and what you’ll see in the Azure Portal.
Microsoft received a lot of feedback to further reduce the cost of storage in the cloud, particularly for data that is rarely accessed but must be retained for operational, legal, or regulatory reasons. Microsoft responding by creating a new tier of Block Blob storage in Azure.
Remember, according to Microsoft, Block Blob storage is:
… used for streaming and storing documents, videos, pictures, backups, and other unstructured text or binary data.
Now there are two kinds of Block Blob storage accounts:
When you create a new ARM storage account in the Azure Portal at https://portal.azure.com, and not in the classic management portal, you get a new experience. You will be asked if you want to create a “Blob storage” account or a “General purpose” storage account.
If you select “Blob storage” then you will select an Access Tier for the storage account, Hot or Cool, and this will affect the pricing of the new storage account.
Replication can have one of three values:
Zone redundant storage (ZRS) is not an option for Block Blob storage accounts.
You cannot modify the hot/cool status of any storage account that was:
Note that you can see the configuration of storage account in the management portal. There are three storage accounts in the below screenshot:
Of the above, only the Block Blob storage account (BlobStorage) can be switched from cool to hot, or vice versa. You can do this by opening the settings of the storage account, browsing to Configuration, and changing the Access Tier setting from Cool to Hot, or vice versa.
You can find the pricing for your desired region, currency and resiliency/replication types of hot/cool storage at the recently updated Azure storage pricing page. In North Europe (Ireland):
If cool storage is so much cheaper then why wouldn’t you use it for storing all of your blobs? The answer lies in how Microsoft describes the use case for cool storage:
In general, any data which lives for a longer period of time and is accessed less than once a month is a perfect candidate for cool storage.
Note the phrase “accessed less than once a month”. This is real archive data, so Microsoft has tuned the pricing of hot versus cold based on your rate of access. Hot storage is more expensive to keep, but cheaper to access than cold storage. For example, in North Europe the pricing of data retrieval (per GB) is:
So the choice is simple:
The obvious case you might want to use is Azure Backup; unfortunately Azure Backup does not support cool storage at this time, but you can vote to change this at the official feedback site.
Developers can modify their software to use cool storage with very little effort; the APIs are unchanged. Some third-party software already can take advantage of the storage option, but I would advise caution on the choice of cool versus hot storage based on the required access rate of the blobs: