Azure Blob storage archive access tier – How much it cost to upload your data?

July 1, 2019

I needed to come up with an estimated cost to store 120TB of data in Azure Blob Storage. Most objects will never need to be retrieved. Few of the objects will be retrieved once or twice a year. It made sense to put these objects in archive access tier instead of hot or cold access tier. If you are interested to know the differences between the three access tier read ‘Azure Blob storage: hot, cool, and archive access tiers‘. Even though I know all objects in the container will reside in archive access tier, I cannot set the default tier of the storage account or the blob container to archive. I can only set it to hot or cold.

Blob storage and GPv2 accounts expose the Access Tier attribute at the account level. This attribute allows you to specify the default access tier as hot or cool for any blob in the storage account that doesn’t have an explicit tier set at the object level.

My only option is to load files with default access tier of the account and then change the access tier from hot/cold to archive. I checked 3 file copy options (AzCopy, Azure Storage Explorer, Azure portal) and none allowed me to load the files directly with archive access tier. This double hop will cost you twice. Once to write to the hot or cold tier and then to switch to archive access tier.

When a blob is moved to a cooler tier (hot->cool, hot->archive, or cool->archive), the operation is billed as a write operation to the destination tier, where the write operation (per 10,000) and data write (per GB) charges of the destination tier apply.

My assumption was also confirmed by Adam Smith in this MSDN Forum Question.

In my case writing 120 TB to hot access tier will cost $314.57. Note here that writing to cold access tier will cost more ($629.15). Moving from hot to archive access tier will cost another $660.60. I am using Azure Storage Calculator. ‘Understanding Windows Azure Storage Billing – Bandwidth, Transactions, and Capacity‘ will help you to find the number of operations and transactions while using calculator.

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