There is a way to do this without downtime for SQL Server.

1. Backup the master database

2. Restore the backup file as a differently named database

3. Detach this database

You now have the mdf and ldf files for the master database that can be used in the same way the article suggests, but without any downtime.

This could even be done as a scheduled job, so you have an up to date master backup that can be easily restored any time.