Rehydration

When a blob is stored in the archive tier, it's considered to be offline and can't be read or modified. In order to read/write this blob you need to move it to the hot or cool tier so that it is online. This can be done in two ways:

• Copy
  Recommended.
  You can copy the archived blob using the "copy blob" or "copy blob from URL" REST APIs
• Change tier
  You can move the blob to an online tier by using the "set blob tier" REST API

This process can take several hours. For optimal performance, it is best to rehydrate large blobs. Rehydrating several small blobs at once might take extra time.

Priority

In the REST APIs for the copy and change tier methods to unarchive blobs, you can specify a priority using the x-ms-rehydrate-priority header with the following options:

• High
  Prioritised over standard requests, can complete in under an hour for blobs under 10gb
• Standard
  Can take up to 15 hours to complete

Copy

Copies the archived blob into an "online" tier so that the data can be accessed. The destination blob must have a different blob name or be in a different container. You cannot overwrite the source blob by copying to the same blob name.

There are also additional restrictions depending on the service version you are using:

• before 2021-02-12
  Copied blob can end up in the same storage account as the original archived blob.
• after 2021-02-12
  Copied blob must end up in a different storage account within the same region.

Change tier

This option "changes" the tier of the blob, rather than copying the archived blob. After initiating the request, it cannot be cancelled. The blob tier will be displayed as archive until the operation completes.