What is the best way to set up Failover site availability when the connection in the DC is down?

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igormukhin2015-06-01 10:58:40

ubuntu

igormukhin, 2015-06-01 10:58:40

Hello!
Situation: the DC loses connection.
Task: to make a failover so that the site works even if the connection with the whole world is lost in the DC.
How to make a failover is clear at first glance - duplicate servers are installed (for backend, db) and the balancer proxies requests to different backends. When one of the backends crashes, it stops processing requests, the load is distributed to the rest.
Here's what's interesting:
1. How to organize the system so that the balancer / frontend is not one, but several and in different DCs? To not have a single point of entry/failure?
2. If this is not possible, how ideologically correct is it to use some kind of DynamicDNS to switch the domain to another IP (with a mirror in another DC) in case of problems? (Downtime is about 1 minute - let's say).
Thank you.

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2 answer(s)

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Igor, 2015-06-01
@merryjane

In the simplest case, round-robin dns will help you. Several entries, each of which leads to a balancer in a separate mode DC. If the DC falls, you will lose only part of the traffic. For the most part, browsers are now smart and can sort out addresses when the first one is unavailable.
In a more complex version, raise dynamic routing and balance routes with weights to the same balancer address in different DCs. If the main DC goes down, the traffic will switch to a route with a lower metric and go to the backup balancer.

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Dan Ivanov, 2015-06-02
@ptchol

If you announce yourself to the world and completely control the network, then you should look at anycast dns.
This will allow you to stop announcing it and remove the load in case of failure / degradation of the performance of services of one of the clusters.
If not, then the option that you described is quite workable. The same Amazonian route53 is able to change the DNS record on the basis of helschecks. Take it, test it, if the speed of the "change" suits you, and you know the approximate number of visitors per month, you can estimate how much this solution will cost.