Azure SQL backup types, retention windows, and configurable limits vary by service tier and deployment option. Always verify exact limits for your tier in the official Azure docs: https://learn.microsoft.com/azure/azure-sql/database/automatic-backups-overview. The concepts here (full, differential, and transaction log backups; PITR; LTR; geo-restore) are broadly applicable.
These backups work together so you can restore a database to a full backup, a more recent differential, or to any point in time within the PITR window by replaying transaction log backups.

- Full backup: the database data files plus the transactional log records required to make the backup consistent.
- Differential backup: only data page changes (delta) since the last full backup.
- Transaction log backup: transaction log records only; used to replay transactions and perform PITR within retention.

- Open the Azure portal and navigate to SQL databases.
- Select the database to inspect (for example, a migrated database).
- From the database page, click the server name to open the server overview.
- On the server overview, choose Backups.

- Point-in-time restore (PITR) retention — set how many days of PITR you require (max varies by service tier; many tiers allow up to 35 days).
- Differential backup frequency — tune differential backup frequency (for example, 24 hours) to balance recovery granularity and storage.
- Long-term retention (LTR) — configure weekly, monthly, and yearly LTR snapshots and their retention durations (LTR supports retention up to 10 years).

When restoring a deleted database, you must restore to the same server or managed instance from which it was deleted. For cross-region recovery when the primary region is inaccessible, use geo-restore instead (this creates a database on a different server/region using geo-replicated backups).
- Azure SQL uses full, differential, and transaction log backups in combination to enable PITR and other restore scenarios.
- Configure PITR retention and differential frequency on the server’s Backups page; enable LTR for long-term archival (up to 10 years).
- For SQL Server on Azure VMs, use the Recovery Services vault and select “SQL on Azure VM” to configure backups: https://learn.microsoft.com/azure/backup/backup-introduction-to-azure-backup.
- Deleted-database restores must target the original server/managed instance; geo-restore is available for region-level failures.
- Azure SQL automatic backups overview: https://learn.microsoft.com/azure/azure-sql/database/automatic-backups-overview
- Point-in-time restore (PITR): https://learn.microsoft.com/azure/azure-sql/database/point-in-time-restore
- Geo-restore overview: https://learn.microsoft.com/azure/azure-sql/database/geo-restore-overview
- Long-term retention (LTR): https://learn.microsoft.com/azure/azure-sql/database/long-term-retention-overview
- Azure Backup (Recovery Services vault): https://learn.microsoft.com/azure/backup/backup-introduction-to-azure-backup