About SQL Server agent grouped backups (legacy SQL Server policies)
Note:
This feature is only available with legacy SQL Server backup policies.
The SQL Server agent provides a method in which multiple databases can be quiesced together and split-off to form a single snapshot. This method minimizes the usage of system resources if the databases exist on a single volume. This happens because the aggregation of constituent files uses one snapshot volume instead of one per database. The method for aggregating database Snapshot Client backups is called backup "grouping".
When databases are backed up in a group, all of the databases are quiesced simultaneously. The constituent files of all databases are backed up to a single storage image under the same backup ID. This means that an "import and copy" procedure would use only one image to export all of the database backups in the group.