Archive Rehydration

Archive rehydration makes data in an offline archive available for reading through the provider’s supported workflow. The operation may change a tier or expose a readable copy. An archive label alone does not imply offline data: Google Cloud Storage Archive supports direct online reads.

For S3 Glacier Flexible Retrieval and Deep Archive, a restore can provide a temporary readable copy while the archived object remains. Azure Archive uses rehydration to an online tier, either in place or through a supported copy workflow. Track the precise object version, operation status, retrieval mode, and any readable-copy expiry. For example, a restore request for an object in S3 Glacier Deep Archive first enters a waiting state. Once restoration completes, the same object can be read through its temporary copy until that copy expires; the archived object remains, so another read after expiry needs another restore. Keeping a permanent online copy requires copying the restored data into an online storage class. In Azure, rehydrating in place instead changes the blob to an online tier; its lifetime is then governed by that tier and the lifecycle policy.

A successful restore request is not a completed recovery. Include waiting, downloading, decrypting, parsing, and rebuilding downstream data in the deadline. Confirm required identities and encryption keys work, then compare the returned bytes with a controlled inventory and execute the intended consumer.

Test representative sources, ages, sizes, versions, and failure paths. A checksum match establishes consistency with its reference, not that every required record was archived. Record findings against exact versions and resolve them. Include retrieval and copy costs, and ensure lifecycle rules do not immediately reverse the recovery operation.

See Storage Tiering, Lifecycle, and Archival for worked examples.

References:

• Microsoft Learn, Blob rehydration from the archive tier
• Google Cloud Storage Documentation, Storage classes
• Amazon S3 User Guide, Restoring an archived object