Each of us has to deal with maintenance, especially “compact” system databases such as log.nsf, admin4.nsf, events4.nsf, ddm.nsf and so on. Yes, just turn off the Domino server and take the compact offline. Depending on the size of the databases, server downtime increases.
However, there is an option to minimize server downtime. Since of Domino 9.0.x, there is a compact with these parameters (for example):
load compact -c log.nsf -REPLICA -RESTART
Using these parameters, a DB replica is executed, on which a compact is performed, and when completed, the Domino server is restarted and this replica is replaced.
This can minimize Domino downtime due to maintenance. I would not use this solution for common applications, but only for system applications.