A comprehensive SIS holds a gold mine of information for a school and its teachers. They are expensive, and some schools piece together a few programs, sometimes items they have created, to meet the most basic needs. An SIS requires initial input of information collected by the registrar in the registration process. Starting right here, there must be IT staff to facilitate the availability of the SIS to all who need it. These same IT persons may have only SIS responsibilities or cross over and also have tasks pertaining to the LMS. The SIS is the repository of information everyone on board needs: directors, principals, facilitators, other administrators, teachers, and students.
My personal experience has been with schools with a true SIS and schools with pieces of technology that perform certain tasks. The full SIS provided a wealth of information to directors, managers and teachers. This was where all transcripts, course enrollments, personal data, and communications with students and their parents was housed. It was extremely effective for the teachers, because it was comprehensive and easily accessed. In schools with no formal SIS, information was housed in a variety of places. These included GoogleDocs for some data and PowerSchool for grades and attendance. Attendance was taken in D2L and then transferred to PowerSchool. There is no doubt that a sophisticated SIS can add significantly to the efficiency of the school. In addition to providing data for the day-to-day operations, it is a powerful planning tool.
We are probably all waiting for the perfect LMS. I have taught using Blackboard, E-College (now Pearson), Moodle and Desire 2 Learn. Each had its great features and each had areas that were lacking. I have often wished that someone would take the very best of each and create THE LMS. The LMS houses what the students and teachers need to function as a learning community. The roles are delineated as instructional administrators, content developers, teachers, facilitators (if student are in a blended learning situation), students and parents.
The crossover of any of these roles depends on the size and resources of the school. I have been content developer and teacher at one school and content developer, departmental coordinator and teacher at another. I have taught where every bit of content was developed in-house and I have taught where some elements of content have been purchased from an outside source. In my experience, the way the SIS and LMS are configured is based largely on the financial resources of the particular school.