To download data from object storage back to the source extents, Veeam Backup & Replication uses the SOBR Download session.
The SOBR Download session is triggered right after you select the Copy to performance tier option; it collects offloaded blocks of data from object storage and copies them back to the on-premises extents. For more information, see Copying to Performance Tier and Downloading to Performance Tier.
Consider the following:
- Before copying data blocks, Veeam Backup & Replication verifies whether any of such blocks exist on any of the extents of your scale-out backup repository. If found, Veeam Backup & Replication will use the existing blocks instead of downloading the exact same data from object storage.
- If a source extent is unable to accommodate data being copied due to lack of free storage space, Veeam Backup & Replication will find another extent in the associated scale-out backup repository that has sufficient storage capacity to receive the data. If your scale-out backup repository has no extents other than the one running out of space, the copy will not be possible.
- If you have removed any of the extents from a scale-out backup repository without evacuating backup files with metadata, the copy will not be possible.
Backup files with metadata are created, as described in Moving Inactive Backup Chains to Object Storage.
- The SOBR Download session results are saved to the configuration database and available for viewing, as described in Viewing Download Job Session Results.
The following figure shows an example of replenishing on-premises storage with the data blocks being copied from the object storage repository.
- The Figure A represents an object storage repository containing blocks of data to be copied.
- The Figure B represents extents that store backup files with metadata to be replenished.