Is it contains either one instance if I visit http://myapp.cloudapp.net/trace.axd on the site hosted on Windows Azure?

It means I cannot read the tr开发者_如何学运维ace from all instance directly?

If your web role has two instances, and you try to navigate to \trace.axd, that request will be load balanced and sent to just one instance. So you're correct, you can't use \trace.axd to see information from all instances of a web role.