What is a full SQL Server database backup and explain the internal process performed?

Answer: A full backup is a complete point in time version of the data and code. It allows the DBA to restore back to that point in time for recovery. Full backups are needed prior to both differential and transaction log backups.

SQL Server follows the below steps during a BACKUP operation:

A full database backup forces a database checkpoint to flush all data to disk.

The backup process reads the data pages and writes them to the backup file.

Once the data reading operation is complete, it reads the Transaction Log.

The full database backup does not contain all of the records from the transaction log. Instead, it chooses only those records that are necessary to make the restored copy of the database transaction consistent. Those records begin either from the latest active transaction or from the checkpoint created by the backup.

The process writes to the system tables in the MSDB database including the Backup LSN and backup history.