Storage Account metrics show blobs in cool tier when everything is in archive tier

Question

Hello,

My project has 2 storage accounts (V2, one in Sweden Central and one in Norway East ) in which blobs are uploaded directly in archive tier ( the default access tier is Cool, but all the uploads are done with archive tier set).

Blobs in these storage accounts are backups from other storage accounts and are uploaded using this command:

await destinationBlob.StartCopyFromUriAsync(new Uri(sourceBlobUrl.TemporaryUrl), accessTier: AccessTier.Archive, cancellationToken: cancellationToken);

Using the Azure Storage Explorer or running Blob Inventory, we can see that all the blobs are in archive. The problem is that when we check the metrics and slit on Blob tier, we can see blobs in cool and we can not figure out why is that.

The storage accounts are not used for any other purpose than storing blobs in archive tier, there are no log files, nothing that is added in cool. The same behavior of these storage accounts can be observed in all 3 subscriptions we are using (internal, stage, production). In Production where the amount of data stored in archive tier is around 100TB, the size of total blobs reported in cool is around 400GB and growing.

Any idea why blobs in cool tier appear in the metrics when nothing is uploaded in cool? We have already opened 2 support tickets to Microsoft and we did not get an answer from them for months.

Answer 1

@Angela Calborean I'm glad that issue got resolved and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to "Accept " the answer.

Issue: "Storage account metrics show blobs in cool tier, but checking each individual blob shows that all of them are in archive tier"
Why are blobs in the Cool tier appearing in the metrics even though all uploads are explicitly done with the Archive tier in two storage accounts located in Sweden Central and Norway East, used solely for storing blobs in the Archive tier, and where metrics indicate a discrepancy with a growing size of blobs reported in Cool tier in multiple subscriptions, despite no intentional data uploads to Cool tier?

Solution: You do not have direct access to the archive stamps (Archive data). The only way you can read their actual data in the archive is by retrieving them to lower tier.However, azure storage stores all archive metadata in cool tier, it is by design. So that you can list the blob and its properties, metadata, and index tags. Metadata for a blob in the archive tier is read-only, while blob index tags can be read or written. Storage costs for metadata of archived blobs will be charged on cool tier rates. Snapshots aren't supported for archived blobs. https://learn.microsoft.com/en-us/azure/storage/blobs/access-tiers-overview#archive-access-tier 

Posting offline discussion.

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