How to sync two or more Mercurial servers?

I want to keep Mercurial servers at 开发者_如何学编程four different locations, and want them to be identical at any given time. Meaning, any change to any of them must be propagated to all other servers. How to do that?

---

You can add an action on the server with an incoming hook.

Hooks allow you to automate tasks when events happen on the repository. Whenever you get a push into the repository, you can push to your mirrors as well.

More on hooks: http://hgbook.red-bean.com/read/handling-repository-events-with-hooks.html