Backup file source if main source is offline?

[j.venning]

Hi everyone, I want to create a web server that uses my server at home for its main source of data. The server sometimes goes offline so I would need the website to switch to a different source of data e.g a different server which is online. If you dont get what I mean, here is a diagram:



IF ONLINE GO TO MAIN SERVER
HTTP REQUEST ---------------------> MAIN SERVER
IF OFFLINE GO TO BACKUP SERVER
---------------------> BACKUP SERVER