> The first sync might take extra long (say 30s) because there could be tons of stuff unsynced.

that would have to be an awful lot of data, or a very slow drive, perhaps a floppy?

your other assumptions are sensible, to an extent. but way back when, we typically had a script that sent a message to all ttys saying "system going down in 30 seconds, please log off" - in fact ALL the other systems i used back then (Dec10, VAX, IBM 4381) did this before the sync (or whatever they did).