Now it's time to get serious. We have discussed all the components that go into a stable server for several pages, and have strongly suggested obtaining multiple spares for each. Well, that applies to the server itself. Not only does this mean having a spare idle server in case of a catastrophic failure, but it means having an online server as well.
Determining excess server inventory isn't quite that simple, but it's fairly close. This is where the project starts to get expensive, but high availability is never cheap; the company itself might depend on it.
Unlike the process we used in Chapter 1, Architectural Considerations, this recipe will focus on server hardware redundancy rather than cluster design. In many ways, this recipe can help augment architectural considerations.