| There is no one right time to patch a system . Rather, the approach needs to be tailored to the situation. For example, in a reactive support situation that requires a patch, modifications should be limited to the smallest change necessary that solves the problem. The engineer involved needs diagnostic tools and a means of retrieving individual patches. By contrast, a person performing a new system installation wants consistency and reliability. For him, a standard bundle of patches may be a better solution. Patch usage models provide a basis for process standardization. They help people involved with patching ”from Help Desk agents to systems administrators to IS managers ”understand how patching works from end to end. And they serve to reinforce good system management practices. While this list is not intended to be comprehensive, it does cover the most common reasons for applying patches. In some cases, the use model refers to portions of other models. This fact reinforces the idea of common process building blocks. HP has produced an excellent White Paper on this subject. If you are bored and lonely one day, you might want to look it over. Full and detailed explanations of each model can be found in Appendix C "Patch Usage Models ”White Paper." The most common reasons for patching include: Whether we know it or not, most of us get involved with patching during a new system installation. HP-UX commonly has the base software as well as recently developed patches loaded on the Installation media. The rest of our experience with patches may be in the realm of reactive patching where we are reacting to problems that have happened on a particular machine. Proactive patching is where we are using patches to try to avoid known problems. Many administrators I know will use the well-worn phrase "why try to fix something that isn't broken?" My response is that it might not be broken now, but HP has seen that in certain circumstances, it will break. In a high availability scenario, you don't want servers to break, ever. Proactive patching can preempt known problems. It should be undertaken frequently, possibly with the regular release of Support Plus media, which is normally on a quarterly basis. The ethics, morals, and logistics of proactive patching are a discussion for another time (over some cold beers). I leave it to you to consider and worry about when you should patch your servers. | 