这是门户网站的文档。  https://docs.microsoft.com/en-us/azure/backup/backup-azure-vms-first -look-arm

Here is a document for the portal. https://docs.microsoft.com/en-us/azure/backup/backup-azure-vms-first-look-arm

在第6步，它甚至每天备份并保留30天。希望这有帮助，因为我没有VM来测试它。 

On step 6 it even has backup daily and retain for 30 days. Hope this helps as I don't have VM's to test this on anymore.