After a server failure before the nightly backup, how many backup sets minimum are required for full restoration?

To determine the minimum number of backup sets required for a full restoration after a server failure, it's essential to understand the backup strategy being employed. In most scenarios, full data protection typically combines both full backups and incremental or differential backups.

A full backup serves as the foundational backup, containing all the data at a particular point in time. If a server fails after this backup and before any subsequent backups (such as incremental backups), restoring from the latest full backup is necessary. However, if only one set was available, it would restore to the state of that last full backup.

Incremental backups capture only the changes made since the last backup, whether full or incremental. Therefore, if you want to restore to the most current point just before the failure, you would need the last full backup alongside all incremental backups taken since that full backup.

In this specific case, having a minimum of three backup sets typically indicates that there is one full backup and at least two incremental backups. The full backup is used to restore the server to a baseline state, while the subsequent incremental backups bring the data up to the point right before the failure.

This pattern highlights the importance of maintaining a structured backup approach that includes both full and incremental backups to ensure a complete restoration capability.