Fault-Tolerant Hardware Versus Software
The following are points to consider when deciding between a fault-tolerant hardware or software solution:
Fault-tolerant software is available only on Windows 2000 Server.
Hardware fault tolerance is faster.
Software fault tolerance is less expensive.
In a hardware fault tolerance implementation, some vendors support hot-swappable disks when there is a disk failure.
Regardless of whether you implement fault tolerance by using hardware or software, implementing fault tolerance does not reduce the need for backups.