DR/BC for web/DB servers


I'm looking for a faster/reliable solution for DR/BC as well as for sclability for my web/db servers. I came across VMWare Infrastructure and other products. The I/O performance concerns me to go with virtual servers. I'm also looking into imaging software such as Acrnois.

Could anyone share their thoughts on how it's being done with bigger names such as google/youtube etc..?

Thank you,
Janakan Rajendran.