Enable root login on Mac OS X

I have a second hard drive in my MacBook Pro that stores the user’s files. To enable state safe manipulation of those data, I like to log as root. This way, I ensure that none of those files will be modified during operation (copy, move, …).

Here’s how to enable root login on Snow Leopard:

• From the  menu, select System Preferences ;
• From the System section, select the Accounts tool ;
• Select the Options option and click the Join button ;
• Click the Open Directory Utility button ;
• Click on the lock and enter the administrator password ;
• In the Edit menu, select the Enable Root User command ;
• Fill-in the root password and click OK.

That’s it!
When you wish to roll-out, use the same procedure but select Disable Root User.

Source: Enabling and using the “root” user in Mac OS X