before they copy a file or a set of data, they have to shut down server so everything would stop and no bug would occur if they do copy paste
you want the server to jack up while they copy and paste your data?
live server cant be interrupted by those things except for gm tools that bans or make in-game announcement and are backup by a fixed set of time like every 30 mins or 1 hour
a GM tool is different from copy pasting data in a server in case you question what is a gm tool.
gm tools refer to things that are given to people with authority to give an item/prize take away item/prize block people who abuse and make in-game announcement and also insert missing cash points (rare cases on MMO but common in mobile games)
while the one you are referring to is something that should be done on the server itself so interrupting it with a copy paste would slow everything down and disturb thousands of players in-game just for 1 data transfer.
lets put it like this and how would they need 24 hours to do it
normal maintenance would be like 5-8 hrs depending on the company
the transfer:
server shuts down first ofc
data that needs to be copied are based on the tickets that are sent and are also recorded by the customer service into a spreadsheet and sent to the developers or the one who handles the server to do the copy pasting
they need to find each player one by one depending also on the type of tools they use and possibly need to alter their AccountID to a new one since the original AccountID is already taken so they either manually edit and paste it on the last AccountID on that server. there are also junk files that should be deleted like friend list or guild that is on the previous server before they transfer so they have to remove it first before making any edit on the transfer. like what i said on the first part, they cant do the copy paste while the server are online because there are new players coming and making a new team so its another entry in AccountID and if they fail to make a unique AccountID then the server will get an error. since making a new team adds a unique AccountID they do the copy pasting by typing every information you have on the previous server one by one on the new server since i think it would make an error on the computation on AccountID unless they edit the computation
there are so many errors that would show up if you do it on a live server so thats what i can tell you for now since i can put like 200~300+ more words about those things based on what i understand on server handling and programming and databases since i am an IT (just an average not a smart guy that knows everything)
after the transfer it is possible that they are testing it on another server to see if there are any bugs that occured after doing the transfer (like what happened on SEA where you dc after x amount of time inside the dungeon that wasn’t there before the transfer)
lets go back to the unfair part that you are saying.
they are saying it is unfair because most or all people who wants to be transferred didn’t use the market in a week or so (to be safe) so they can avail for the free 1 time transfer. if you didn’t bother using 10 mins of your whole life just reading the news in ToS because its been there for like 2-3 weeks. so if you didn’t bother reading it then its your fault actually.
2-3 weeks of preparation is actually long to be fair and if you missed it then no transfer for you until they announce another one in the future (2-3 months later i think)
this is also the same with discount promos. you cant use the discount after the promo ends and if they allow you it’ll be unfair for those who bought it during the promo. you just have to wait for the next promo if you want to participate. its not worth your time at first but after you knew about it you come and it is already over so pretty much again, your fault for not taking the time