How do I restore a site using drush? I have been learning drush and I loving it. i am having a tough time understanding how to backup and restore my site. Often I bork my site and just need to quickly restore it. These are the steps I am following and I am met with the following error:

Destination directory /Users/Nigel/Sites/sitename/ already exists.      [error]

Unable to restore files to /Users/Nigel/Sites/sitename/  



cd to my Drupal installation.
Create a Drush archive dump (code and db in one)

drush ard
Grab my backup (e.g. sitename.20130221_055426.tar.gz) and place it
back into the root of my Drupal installation

drush arr sitename.20130221_055426.tar.gz


There is a similar question How do I use Drush correctly to restore a site via the arr command? , however the issue and thus the answer has to do with different db credentials, rather than the steps to restore a site.

I am obviously doing something completely wrong here. Any help would be appreciated.
Try adding --overwrite to your restore command, that will let you overwrite an existing site.