Backup SQL Server database using WITH FORMAT

Question

I'm having a bit of trouble understanding the purpose of the WITH FORMAT option of the SQL Server BACKUP DATABASE command.

Using the MSDN example:

USE AdventureWorks2012;
GO

BACKUP DATABASE AdventureWorks2012
    TO DISK = 'Z:\SQLServerBackups\AdventureWorks2012.Bak'
       WITH FORMAT,
            MEDIANAME = 'Z_SQLServerBackups',
            NAME = 'Full Backup of AdventureWorks2012';
GO

I understand this deletes any existing backups and creates a new one.

If I was to omit the WITH FORMAT line, and I already had a backup at Z:\SQLServerBackups\AdventureWorks2012.Bak, what does this mean to my backup?

Is it incremental or does it overwrite with a full one?

Answer 1

It's a full backup, essentially appended to the file if it exists already, you'll see a File number 2 reference when you run it, and you'll see the backup file double in size. Each backup is independent of each other and either can be restored.