How to use long term archival storage with Azure and Storage Explorer

Tags Azure cloud


Archive Storage is built as a scalable service for cost-effective storing of rarely accessed data for long periods of time. Cold data such as application backups, healthcare records, autonomous driving recordings, etc. that might have been previously deleted could be stored in Azure Storage’s Archive tier in an offline state, then rehydrated to an online tier when needed. It is optimized for storing data that is rarely accessed and stored for at least 180 days with flexible latency requirements, on the order of hours.

Table of Contents

Getting Started

Before you get started with archive storage, you'll need to have an active Azure subscription and have Storage Explorer installed and configured. For information about completing these tasks, please see the following articles:

  1. Sign up for Azure 
    • NOTE: You'll need a CFOAP to obtain a subscription
  2. Install Storage Explorer on your Windows/Mac/Linux
  3. Learn how to use Storage Explorer

The Archive access tier has the lowest storage cost but higher data retrieval costs compared to hot and cool tiers. Data must remain in the archive tier for at least 180 days or be subject to an early deletion charge. Data in the archive tier can take several hours to retrieve depending on the specified rehydration priority. For small objects, a high-priority rehydrate may retrieve the object from the archive in under an hour.

While a blob is in archive storage, the blob data is offline and can't be read or modified. To read or download a blob in the archive, you must first rehydrate it to an online tier. You can't take snapshots of a blob in archive storage. However, the blob metadata remains online and available, allowing you to list the blob, its properties, metadata, and blob index tags. Setting or modifying the blob metadata while in an archive isn't allowed.

Example usage scenarios for the archive access tier include:

  • Long-term backup, secondary backup, and archival data sets
  • Original (raw) data that must be preserved, even after it has been processed into a final usable form
  • Compliance and archival data that needs to be stored for a long time and is hardly ever accessed

NOTE: The archive tier is not supported for ZRS, GZRS, or RA-GZRS accounts. Migrating from LRS to GRS is supported as long as no blobs were moved to the archive tier while the account was set to LRS. An account can be moved back to GRS if the update is done less than 30 days from the time the account became LRS, and no blobs were moved to the archive tier while the account was set to LRS.

Setting files for Archive Storage

  1. Launch Storage Explorer
  2. In Storage Explorer, select View > Account Management or select the Manage Accounts button.

    explorer menu highlighting manage accounts button
  3. ACCOUNT MANAGEMENT now displays all the Azure accounts you're signed in to. To connect to another account, select Add an account.
  4. The Connect to Azure Storage dialog opens. In the Select Resource panel, select Subscription.

    select resource screen highlighting subscription sign in button
  5. In the Select Azure Environment panel, select an Azure environment to sign in to. You can sign in to global Azure, a national cloud, or an Azure Stack instance. Then select Next.
    select azure environment panel with radio button for azure
  6. When prompted to log in, use your email address and UIC Common Password.

    microsoft sign in screen with field for U I C email address

    U I C sign in page with fields for email and password
  7. After you successfully sign in with an Azure account, the account and the Azure subscriptions associated with that account appear under ACCOUNT MANAGEMENT. Select the Azure subscriptions that you want to work with, and then select Apply.

    account management screen with list of resources for your subscriptions
  8. Upload Files to Blob storage/view Existing blobs

Upload blobs to the container

Blob storage supports block blobs, append blobs, and page blobs. VHD files used to back IaaS VMs are page blobs. Append blobs are used for logging, such as when you want to write to a file and then keep adding more information. Most files stored in Blob storage are block blobs.

  • On the container ribbon, select Upload. This operation gives you the option to upload a folder or a file.
  • Choose the files or folder to upload. Select the blob type. Acceptable choices are Append, Page, or Block blob.
  • If uploading a .vhd or .vhdx file, choose Upload .vhd/.vhdx files as page blobs (recommended).
  • In the Upload to folder (optional) field either a folder name to store the files or folders in a folder under the container. If no folder is chosen, the files are uploaded directly under the container.

example activities screen

  • When you select OK, the files selected are queued to upload, each file is uploaded. When the upload is complete, the results are shown in the Activities window.

View blobs in a container

  • In the Azure Storage Explorer application, select a container under a storage account. The main pane shows a list of the blobs in the selected container.

example screen to view blobs in container

  • Right click on a file or folder and select "Change Access Tier"

identifying the change access tier option in the dropdown menu

  • Select the "Archive" Tier and click "apply"

Update Access Tier screen highlighting archive radio button and apply button


NOTE:  Take care to monitor costs

General Pricing Information

All storage accounts use a pricing model for block blob storage based on the tier of each blob. Keep in mind the following billing considerations:

  • Storage costs: In addition to the amount of data stored, the cost of storing data varies depending on the access tier. The per-gigabyte cost decreases as the tier gets cooler.

  • Data access costs: Data access charges increase as the tier gets cooler. For data in the cool and archive access tier, you're charged a per-gigabyte data access charge for reads.

  • Transaction costs: There's a per-transaction charge for all tiers that increases as the tier gets cooler.

  • Geo-replication data transfer costs: This charge only applies to accounts with geo-replication configured, including GRS and RA-GRS. Geo-replication data transfer incurs a per-gigabyte charge.

  • Outbound data transfer costs: Outbound data transfers (data that is transferred out of an Azure region) incur billing for bandwidth usage on a per-gigabyte basis, consistent with general-purpose storage accounts.

  • Changing the access tier: Changing the account access tier will result in tier change charges for all blobs that don't have an explicit tier set.

    Changing the access tier for a blob when versioning is enabled, or if the blob has snapshots, may result in additional charges.

Archive Early Deletion

Any blob that is moved into the cool tier (GPv2 accounts only) is subject to a cool early deletion period of 30 days. Any blob that is moved into the archive tier is subject to an archive early deletion period of 180 days. This charge is prorated. For example, if a blob is moved to archive and then deleted or moved to the hot tier after 45 days, you'll be charged an early deletion fee equivalent to 135 (180 minus 45) days of storing that blob in archive.

There are some details when moving between the cool and archive tiers:

  1. If a blob is inferred as cool based on the storage account's default access tier and the blob is moved to archive, there is no early deletion charge.
  2. If a blob is explicitly moved to the cool tier and then moved to archive, the early deletion charge applies.

Calculate the early deletion time by using the Last-Modified blob property, if there have been no access tier changes. Otherwise, use when the access tier was last modified to cool or archive by viewing the blob property: access-tier-change-time.

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Article ID: 2211
Tue 5/11/21 9:38 AM
Wed 5/19/21 5:31 PM

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