
Ask HN: Why do some websites need to be taken offline for maintenance? - superasn
I was just browsing italki.com and there has been a notice since morning that the website will be going down for maintenance (it is completely offline now)<p>It&#x27;s a pretty huge site I think with lots of revenue and users and it&#x27;s probably losing money for the time it&#x27;s down.<p>So I was just wondering why do some websites need to be taken down while others like Facebook, Gmail, etc never once have shown me such notice yet upgrade seamlessly?
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davismwfl
This used to be normal, you'd see an email come out a couple weeks in advance
and a banner notice on the site, and then a site would go down on like a
Sunday or Monday morning night between 1 and 3-4am ET in the US to try and
minimize disruption.

The key reasons were as others said, but in my personal experience generally
data service/schema related where a key data source would be offline for a
period of time was the primary cause. One thing not mentioned is hardware
upgrades has always been a key driver of this type of maintenance. Self hosted
systems have to be transferred across hardware and brought back online and
tested. This still happens today for many larger enterprises as upgrading to
the latest hardware to support your SQL Server or Oracle database comes down
to cost. They can go down for 2-3 hours for the switchover, OR spend 6-8 weeks
engineering & testing a non-downtime failover. And the math is simple, most
businesses don't have a true 24/7 need to be online and the don't make money
24/7 online, so this is still a solid reason and solution in those cases.

At one company I consulted at we gave them an option to upgrade their
relational database solution (hardware + software) with 0 downtime, but it
would take around 700 man hours to setup and test, or they could go offline
for `4 hours and be back online. They were a B2B company and said the
difference in cost was not worth it and went down for a few hours over a
weekend instead, which honestly made far more sense to me. They did have
clients that accessed the system overnight, but they just sent out a notice
and no one cared.

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superasn
I guess that makes most sense that they are hosted on their own servers and
not cloud. I'd also bet it's mostly a database thing. Better to not let users
write anything new than to lose their data which I'm sure would cause more
hassle.

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byoung2
Bigger sites are more likely to use microservices and multiple failovers so
individual components can be upgraded without downtime. Smaller sites likely
have a single point of failure that needs to go down to make changes (e.g. 1
single master database that needs to be write locked for a schema change).

~~~
aynsof
This isn't limited to just smaller sites. Many slower-moving organizations,
e.g. government and banks, aren't yet up-to-date with zero-downtime
deployments.

