Best way to perform DB backups
 

I am currently trying to put together an automated backup plan for my server (dedicated so I can do anything), and need some advice.

The instructions here are fairly self explanatory:

http://www.vbulletin.com/docs/html/m...nce_ssh_backup

I currently run this through a scheduled batch script (this is a windows box)

However I have a question, this method of backup takes around 5 minutes (which is fair enough as the final db backup file is around 500mb). The thing that concerns me is that while this backup is in process the site is still "live" so people are still hitting the DB, will this backup process still work reliably on a live site, or should the site be shutdown during the backup?

If the latter, how can I gracefully shutdown the site (i.e. display the normal "site is down messages" available through acp), from an external process.