information about the mac application db

docs/operations-guide/running-the-metabase-mac-app.md

@@ -24,3 +24,10 @@ Give the application a moment to finish initializing and then you should see the
 ![macwelcome](images/MacWelcome.png)
 
 Now that you’ve installed Metabase, it’s time to [set it up and connect it to your database](../setting-up-metabase.md).
+
+### The application database
+
+The application database lives on your filesystem, at 
+`~/Library/Application Support/Metabase/metabase.db.h2.db`
+
+If you want to delete it, back it up, or replace it with an old backup, shut down the application and then delete, copy or replace the file.