1. Microsoft Learn
"Automated backups in Azure SQL Database": This document outlines the backup strategy used by Azure SQL. It states
"Azure SQL Database and SQL Managed Instance use SQL Server technology to create full backups every week
differential backups every 12-24 hours
and transaction log backups approximately every 10 minutes." This confirms that differential backups are a fundamental type used in the automated solution that provides high availability.
2. Microsoft Learn
"Differential Backups (SQL Server)": This document explains the purpose of differential backups. Under the "Overview of differential backups" section
it states
"This can speed up the process of restoring a database because fewer log backups have to be applied." This directly supports the reasoning that differential backups improve RTO
a key component of availability.
3. Microsoft Learn
"Recover a database using automated database backups": This page describes the restore process. It confirms that PITR is the method of recovery: "Point-in-time restore (PITR) allows you to restore a database... to an earlier point in time." This distinguishes the restore method from the backup types.
4. Microsoft Learn
"Long-term retention overview": This document clarifies the purpose of LTR. The overview section states
"Many applications have regulatory
compliance
or other business purposes that require you to retain database backups beyond the 1-35 days provided by short-term retention." This positions LTR for archival
not for immediate availability.