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 backup data.
Object storage repositories are cloud-based and on-premises storage systems that you can employ to keep your backup data. Also, you can use Azure Blob Storage Archive access tier, Amazon S3 Glacier and Amazon S3 Glacier Deep Archive storage classes as a target for backup copy jobs.