Data replication = Fault Tolerance?

Hi all. We use Informix Online (soon to be 7.1) and are interested in fault tolerant systems. We already intend to mirror our disks at the Unix level, but would also like a primary / secondary system setup whereby if, for example a processor board or memory chip blows up, then it will be possible for the secondary to be used (within minutes of the failure) while the primary system is being fixed. Is anybody using Informix data replication for this purpose and is it working for you?