The VLE/LMS is such an important resource that for almost any institution downtime is unpopular. Despite this if you are self hosted or managed hosted downtime is inevitable in order to apply upgrades and take care of maintenance.
We negotiate our summer upgrade downtime in January. We do this by identifying possible weekends between the end of semester 2 exams and the start of our summer presessional teaching. Then we put those dates to deans for education and admin leaders in each faculty and ask them to vote on which weekend works best for them. The option with the most votes is then chosen.
Subsequently we announce this to users via a mailing list, and through other communications channels such as our Institutional Portal, and social media such as blogs, Facebook, twitter, the student union and so on.
All communications point to central Upgrade 2017 page where we will place all relevant information. This year’s page is at http://go.soton.ac.uk/bb2017