what if the whole region goes down? HA and DR recovery will not work in this case

“If your applications require high disaster recovery capabilities, we recommend that you deploy your instances in different zones of the same region.” - this is from the docs https://www.alibabacloud.com/help/doc-detail/40654.html



i dont understand why this is recommended by Alibaba, what happens if the whole region goes down? in aws they recommend to spread over regions , not only zones. only this will ensure complete disaster recovery.

Different Zone in same regional will give you the fastest HA / DR backup site going up to pick up the traffic.  


In Alibaba datacenter, different zone in same regional are running in independent power sources and datalink.  So ZoneA down doesn't means ZoneB will be impacted.


Understand you concern, if the whole region (or country) got impact, both Zone will be down.  So in your HA / DR design, other than different zone in same region, you may also add a 1 more level up DR site in other region.  It all depends on the SLA and avalability you need in your system.


Hope this answer your questions.