The backup infrastructure of Veeam Backup for Microsoft 365 consists of the following:
Backup proxy servers are auxiliary machines that you can configure to effectively manage network traffic.
Backup repositories are storage systems that you can add to the Veeam Backup for Microsoft 365 backup infrastructure to keep your backups and backup copies.
Object storage is cloud-based or on-premises storage system that you can employ to keep your backups and backup copies. Keep in mind that you can use Azure Blob Storage Archive access tier, Amazon S3 Glacier Instant Retrieval, Amazon S3 Glacier Flexible Retrieval and Amazon S3 Glacier Deep Archive storage classes only as a target for backup copy jobs.