From SkyServer to SciServer

Twenty years ago, work commenced on the Sloan Digital Sky Survey. The project aimed to collect a statistically complete dataset over a large fraction of the sky and turn it into an open data resource for the world's astronomy community. There were few examples to learn from, and those of us who worked on it had to invent much of the system ourselves. The project has made fundamental changes to astronomy, and we are now faced with the problem of ensuring that the data will be preserved and kept in active use for another 20 years. In redesigning this very large, open archive of data, we made a system that is able to serve a much broader set of communities. In this article, I discuss what we have learned by rebuilding a massive dataset that is available to an increasingly sophisticated set of users, and how we have been challenged and motivated to incorporate more of the patterns of data analytics required by contemporary science.