Answer
For the database tier specifically, relying on Azure's own VM-level backup service alone isn't considered a safe, sufficient approach — instead, enable Oracle archive log mode and use Oracle's own RMAN mechanism for incremental and full database backups, for both production and non-production instances, with an appropriate RMAN retention policy sized against available VM disk space; RMAN backups can optionally be written out to Azure Blob Storage for additional off-VM resiliency, rather than relying purely on local VM disk. For the middleware/application-server tier, VM-level snapshots — especially one taken right before applying an update or delivery — plus regularly scheduled automated backups, for example via the OS's own task scheduler, are the generally recommended approach.