Rehydrate blob data from the archive tier

While a blob is in the archive access tier, it's considered offline and can't be read or modified. The blob metadata remains online and available, allowing you to list the blob and its properties. Reading and modifying blob data is only available with online tiers such as hot or cool. There are two options to retrieve and access data stored in the archive access tier.

  1. Rehydrate an archived blob to an online tier - Rehydrate an archive blob to hot or cool by changing its tier using the Set Blob Tier operation.
  2. Copy an archived blob to an online tier - Create a new copy of an archive blob by using the Copy Blob operation. Specify a different blob name and a destination tier of hot or cool.

For more information on tiers, see Azure Blob storage: hot, cool, and archive access tiers.

Rehydrate an archived blob to an online tier

To read data in archive storage, you must first change the tier of the blob to hot or cool. This process is known as rehydration and can take hours to complete. We recommend large blob sizes for optimal rehydration performance. Rehydrating several small blobs concurrently may add additional time. There are currently two rehydrate priorities, High (preview) and Standard, which can be set via the optional x-ms-rehydrate-priority property on a Set Blob Tier or Copy Blob operation.

  • Standard priority: The rehydration request will be processed in the order it was received and may take up to 15 hours.
  • High priority (preview): The rehydration request will be prioritized over Standard requests and may finish in under 1 hour. High priority may take longer than 1 hour, depending on blob size and current demand. High priority requests are guaranteed to be prioritized over Standard priority requests.

Note

Standard priority is the default rehydration option for archive. High priority is a faster option that will cost more than Standard priority rehydration and is usually reserved for use in emergency data restoration situations.

Once a rehydration request is initiated, it cannot be canceled. During rehydration, you may check the Archive Status blob property to confirm if the tier has changed. The status reads "rehydrate-pending-to-hot" or "rehydrate-pending-to-cool" depending on the destination tier. Upon completion, the archive status property is removed, and the Access Tier blob property reflects the new hot or cool tier.

Copy an archived blob to an online tier

If you don't want to rehydrate your archive blob, you can choose to do a Copy Blob operation. Your original blob will remain unmodified in archive while a new blob is created in the online hot or cool tier for you to work on. In the Copy Blob operation, you may also set the optional x-ms-rehydrate-priority property to Standard or High (preview) to specify the priority at which you want your blob copy created.

Archive blobs can only be copied to online destination tiers within the same storage account. Copying an archive blob to another archive blob is not supported.

Copying a blob from archive can take hours to complete depending on the rehydrate priority selected. Behind the scenes, the Copy Blob operation reads your archive source blob to create a new online blob in the selected destination tier. The new blob may be visible when you list blobs but the data is not available until the read from the source archive blob is complete and data is written to the new online destination blob. The new blob is as an independent copy and any modification or deletion to it does not affect the source archive blob.

Pricing and billing

Rehydrating blobs out of archive into hot or cool tiers are charged as read operations and data retrieval. Using High priority (preview) has higher operation and data retrieval costs compared to standard priority. High priority rehydration shows up as a separate line item on your bill. If a high priority request to return an archive blob of a few gigabytes takes over 5 hours, you won't be charged the high priority retrieval rate. However, standard retrieval rates still apply as the rehydration was prioritized over other requests.

Copying blobs from archive into hot or cool tiers are charged as read operations and data retrieval. A write operation is charged for the creation of the new blob copy. Early deletion fees don't apply when you copy to an online blob because the source blob remains unmodified in the archive tier. High priority retrieval charges do apply if selected.

Blobs in the archive tier should be stored for a minimum of 180 days. Deleting or rehydrating archived blobs before 180 days will incur early deletion fees.

Note

For more information about pricing for block blobs and data rehydration, see Azure Storage Pricing. For more information on outbound data transfer charges, see Data Transfers Pricing Details.

Quickstart scenarios

Rehydrate an archive blob to an online tier

  1. Sign in to the Azure portal.

  2. In the Azure portal, search for and select All Resources.

  3. Select your storage account.

  4. Select your container and then select your blob.

  5. In the Blob properties, select Change tier.

  6. Select the Hot or Cool access tier.

  7. Select a Rehydrate Priority of Standard or High.

  8. Select Save at the bottom.

Change storage account tier

Copy an archive blob to a new blob with an online tier

The following PowerShell script can be used to copy an archive blob to a new blob within the same storage account. The $rgName variable must be initialized with your resource group name. The $accountName variable must be initialized with your storage account name. The $srcContainerName and $destContainerName variables must be initialized with your container names. The $srcBlobName and $destBlobName variables must be initialized with your blob names.

#Initialize the following with your resource group, storage account, container, and blob names
$rgName = ""
$accountName = ""
$srcContainerName = ""
$destContainerName = ""
$srcBlobName == ""
$destBlobName == ""

#Select the storage account and get the context
$storageAccount =Get-AzStorageAccount -ResourceGroupName $rgName -Name $accountName
$ctx = $storageAccount.Context

#Copy source blob to a new destination blob with access tier hot using standard rehydrate priority
Start-AzStorageBlobCopy -SrcContainer $srcContainerName -SrcBlob $srcBlobName -DestContainer $destContainerName -DestBlob $destBlobName -StandardBlobTier Hot -RehydratePriority Standard -Context $ctx

Next Steps