The easiest way would be to get two VPSes or small dedicated servers from separate providers and use the DNS clustering option on all your servers to sync DNS zones with the two nameservers, then your clients can use those nameservers. We have worked with setups like this in the past with very good results. HTH,
MediaLayer, LLC - www.medialayer.comLearn how we can make your website load faster, translating to better conversion rates for your business!
The pioneers of optimized web hosting, featuring LiteSpeed Web Server & SSD Storage - Celebrating 10 Years in Business