I have 96 different archiving objects that are archived in regular intervals.
We operate globally 24/7, there is no second left to get a downtime for archiving.
Archiving execution does not require any downtime. You can interrupt archiving jobs, during peak times if you need. This can be done from customizing of archiving object independent technical settings (can be accessed from SARA) . Only a real database reorganization may require some downtime.