I am developing a site for a client who is emphasizing "no downtime allowed".
Now even cloud hosting doesn't provide a 100% up-time promise, so I've been thinking about mirrored hosting, where if one host goes down, the other takes over. I am unsure how I'd go about setting the DNS to switch on an outage and this is running low budget, as it's a non-profit organization.
If anyone has experience doing this, I'd like to know the best way to go about it.
The site is LAMP. I did think about adding disallow in the robots.txt for the duplicate site to avoid SEO penalties, but other than that am running blind, so any advice would be gladly received.