This is something I never understood in websites, or in web in general. Websites down for updates.
I use this ways:
when updating a website, update everything to /websiteNEW
after its done, rename /website to /websiteOLD and rename /websiteNEW to /website
down for less than 1 min
with servers, you can use the same approach, with machines....
Hoping it will be back online soon...