This article answers frequently asked questions about Azure Blob Backup. For more information on the Azure Blob backup region availability, supported scenarios, and limitations, see the support matrix.
Why does Azure Backup require to keep all versions for Blob backups?
Azure Backup doesn’t manage blob versioning because it’s a storage account feature. When you enable vaulted backup, Azure Backup uses the Object Replication Service (ORS) to replicate blobs, including all versions, to the Backup Vault. The Backup Vault applies retention policies, such as 42 days, at the backup layer and not at the source storage account. Azure Backup doesn't change versioning settings in the storage account, as there might be independent compliance or operational requirements for retaining versions.
Does Backup vault reconcile or delete older blob versions in the source account?
No, the Backup vault doesn't delete or reconcile blob versions in the source storage account. The retention policy applies only to restore points stored in the vault. For blob version cleanup in the source account, manage it separately using Lifecycle Management (LCM) policies or manual configuration.
Can I align blob versioning retention with my backup policy, such as 42 days?
Yes, you can configure blob version retention in the storage account, but it works independently of the backup policy.
For operational backup, set version retention to backup retention plus seven days. For example, if backup retention is 30 days, set version retention to 37 days.
For vaulted backup only, reduce version retention after the first successful backup. We recommend you to keep versions for at least seven days after backup completion, or longer for large accounts with frequent changes.
If you use both operational and vaulted backup, apply the higher of the two retention requirements.
What is the impact on existing recovery points when I modify the Backup policy?
With the modification of backup instance, you can assign new policy. Policy are applied only on future recovery points. Past recovery points are still retained as per the previous policy's retention period.
What happens when account has blobs in archive tier?
Archive blobs present before backup is configured are skipped during backup. This behavior is expected and does not cause failures, delays, or errors in the backup job. If blobs are moved to archive after backup configuration, the backup copy in the vault will not inherit the Archive tier, and backup continues without issues.