akhasheni, unmanaging a node prevents the poller from event attempting to contact the node. Thus, there is no new information coming in concerning response time, application status or netflow details. This causes gaps in your graphs.
Not sure where this came from. What graphs do I want to keep while the Solarwinds server is in maintenance?
I'd recommend attending the new Orion 102 class on Reporting and Alerting. Understanding how alerting works (and suppression) will highlight the difference between the two methods. You'll find the classes available for registration in your customer portal.
The original question was about the maintenance of the Solarwinds server, not managed devices. Leon Adato's excellent suggestion applies to the latter, i.e. helps solve a different problem than mine. In my situation, unmanaging the server is quite a bit simpler and achieves the same goal.
(Thanks for the suggestion to get the 102 training: was already planning on doing that. In turn, may I suggest reading the original question before doing that in the future? )