Application management allows the system to fail and restart the software just as failed hardware would be treated. All of the infrastructure described still does not result in a five-nines available system. The previous availability budget for a five-nines system allocates 1 minute per year for system upgrades. The ability to do online software upgrades is essential to reach this goal. Since very few systems are truly stand-alone, the final piece to achieving five nines is an interface to a management network.
Fault management is best when approached hierarchically.
Therefore, such a construction generally will provide the best results. Equally open software for high availability is also becoming more common. One source of this software is from vendors creating highly available OSes. Many vendors are working on such efforts but none have announced any products, though this picture will be very different in 2001. While some products may implement most of the required components, the user still must develop the procedures and policies for the management of the target platform.