Rehydrate blob data from the archive tier

While a blob is in the archive access tier, it's considered to be offline and can't be read or modified.
In order to read or modify data in an archived blob, you must first rehydrate the blob to an online tier, either the hot or cool tier.
There are two options for rehydrating a blob that is stored in the archive tier:
Copy an archived blob to an online tier: You can rehydrate an archived blob by copying it to a new blob in the hot or cool tier with the Copy Blob or Copy Blob from URL operation. Microsoft recommends this option for most scenarios.
Change a blob's access tier to an online tier: You can rehydrate an archived blob to hot or cool by changing its tier using the Set Blob Tier operation.
Rehydrating a blob from the archive tier can take several hours to complete. Microsoft recommends rehydrating larger blobs for optimal performance. Rehydrating several small blobs concurrently might require extra time.

Rehydration priority

When you rehydrate a blob, you can set the priority for the rehydration operation via the optional x-ms-rehydrate-priority header on a Set Blob Tier or Copy Blob/Copy Blob From URL operation.
Rehydration priority options include:
Standard priority: The rehydration request is processed in the order it was received and might take up to 15 hours.
High priority: The rehydration request is prioritized over standard priority requests and might complete in under one hour for objects under 10 GB in size.
To check the rehydration priority while the rehydration operation is underway, call Get Blob Properties to return the value of the x-ms-rehydrate-priority header. The rehydration priority property returns either Standard or High.

When you copy an archived blob to a new blob in an online tier, the source blob remains unmodified in the archive tier.
You must copy the archived blob to a new blob with a different name or to a different container.
You can't overwrite the source blob by copying to the same blob.
Copying an archived blob to an online destination tier is supported within the same storage account only.
You can't copy an archived blob to a destination blob that is also in the archive tier.

Once a Set Blob Tier request is initiated, it can't be canceled. During the rehydration operation, the blob's access tier setting continues to show as archived until the rehydration process is complete.
Changing a blob's tier doesn't affect its last modified time. If there is a lifecycle management policy in effect for the storage account, then rehydrating a blob with Set Blob Tier can result in a scenario where the lifecycle policy moves the blob back to the archive tier after rehydration because the last modified time is beyond the threshold set for the policy.