Hey Guys,

I'm maintaining a website for a company and since the software running this website is still pretty young I have to make updates pretty frequently. The problem is that while I'm updating the php code and the database the site is down.

One solution to point the domain to a temporary version of the site while I'm maintaining it but I really don't want to do that manually.

My question now is if there's any software (open source preferably) out there to update and maintain a web application while avoiding any downtime (facebook for example is updated frequently and I'm assuming that they have some sort of sophisticated system to update their code without interrupting the access).

Also, I don't want to replace every file over and over again so it would be cool if this tool thingy keeps track of changes and only updates files that were changed.

I'd be glad for any help or advice!!
Regards!