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This refers to GCP Http(s) Global Load balancing tutorial here. This example shows cross region content based load balancing. I want to check if a similar configuration(based on URL maps) can be used to set up a DR site for an application in another region. For example,

  • An instance group in europe-west3 region (Primary). URL map entry added at the time of load balancer configuration.
  • Another instance group in europe-west4 region (DR).

The idea is to update the URL map entry to point to the second (DR) instance group when a DR procedure is invoked.

Question

  1. Assuming the DR instance group is always up(active), how long does it take for a URL map entry update to start routing traffic to the second(DR) instance group?
  2. Is there another way to start routing traffic to the second instance group without a URL map update? Is it possible to configure a DNS setting to create a similar effect?

Update 15Oct2019

At the moment, the best option appears to be setting up a multi region deployment with URL map configured to both regions. GFEs will ensure that traffic is served to users from the primary region - assuming that the primary region is closest to users. However there is a chance of traffic overflow to secondary(DR) region due to reasons other than a DR trigger - as listed in this useful article - which needs to be accounted for.

Cyac
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1 Answers1

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There is different way to set up a DR. According with your acceptable downtime requirement, the solution aren't the same. There is too few details here for providing you a sharp answer.

In any case, the load balancer is better designed for serving different region in the same time and thus having a Hot DR or for serving with the lowest latency the users (indeed, the global load balancer route the request to the closest region from the user)

In you case, if you want to update the URL maps, there will be a not null downtime. By the way I recommend you to use your #2 and to play with DNS. Your DNS switch will take a time, you will have time to start your VM, and you can save money by don't having always on DR region.

Here a good video from Google, others are coming, subscribe for the warm and hot DR example (maybe released next week!)

guillaume blaquiere
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  • thanks for the video link. I will check # 2 but the main concern there is the time taken for DNS level switchover. I do realize that for an active/hot DR it is possible to have URL maps configured to both regions. The only downside I see is traffic can flow to the DR region even if a DR threshold is not reached. I am adding more details and reference in the question itself. – Cyac Oct 15 '19 at 06:30