What is the easiest option for migrating a dozen sites?

Question

Domain Name System

There is a VPS, 2 IP addresses, own ns are configured.
Need to move to another VPS, which option is easier?
Sites should not stop working.

UPD
Let's assume the sites are php + mysql.
and the database can be updated regularly...

Answer 1

Смотря что там за сайты.
Если это обычные корпоративные сайтики, то ручками на другой хост, а потом переводим DNS и пользователь не заметит ничего.
Иначе нужно больше информации...

Answer 2

I don't understand what dns has to do with it.
Absolutely without downtime will not work.
1) make a copy of the site on the second server
2) cut down the site on both servers (503 and that's it).
3) turn on proxy_pass on the old server
4) update the database
5) turn on the site on the new server.
Downtime will be == base transfer time.

Answer 3

If the site control panels are the same - make a backup on one and deploy to another, otherwise - do it all by hand (dump the database and archive the files).
Then, check the sites on the new VPS through the locally-registered DNS (hosts) and when everything works, transfer the public DNS to the new site (IP).