We will be upgrading from 5.0.45 to 5.1. What will the expected down time be for this upgrade. We run 24x7, literally, and have a hard time finding any time for maintenance.
Any help or comments will be appreciated.
Based on the information you've provided so far, I'd allow six months. If you can provide more deails such as the number of servers, databases, gigabytes, tables, applications, etc. I could probably refine that estimate to something more accurate. The problem is that without knowing exactly what you have in terms of data, hardware, talent, etc. all I know how to do is guess.