Backup requirements for a database: Level 0 backup on Sunday Cumulative incremental level 1 backup on Monday, Wednesday, and Saturday * Differential incremental level 1 backup on Tuesday, Thursday…

A Level 0 backup contains all blocks that have ever been used (allocated and written to) in the datafiles, making it a full backup of the used data, not necessarily all blocks that have merely been formatted.

A Level 0 backup acts as the baseline for all subsequent incremental backups. While it contains all used blocks, from the perspective of the incremental strategy, it effectively signifies that all blocks are 'changed' or form a new starting point, rendering previous Level 1 incremental states irrelevant for a recovery path that begins from this Level 0.

This statement is an incomplete description; a Level 1 differential backup on Tuesday, Thursday, and Friday contains all blocks that have been changed since the *most recent Level 0 or Level 1 backup* of any type.

A Level 1 cumulative incremental backup backs up all blocks that have changed since the most recent Level 0 backup. In this strategy, the Level 1 cumulative backups on Monday, Wednesday, and Saturday would each capture all changes made since the Level 0 backup on Sunday.

A Level 1 differential incremental backup backs up all blocks that have changed since the most recent Level 0 or Level 1 backup of any type. In this strategy, the Level 1 differential backups on Tuesday, Thursday, and Friday would capture changes since their immediate preceding Level 0 or Level 1 backup.