Hardware will always fail at some point. You can either add extra resources elsewhere, or deal with that inevitable downtime. Both are reasonable, depending on the impact of downtime.
It's not paying double. Take the total number of instances serving the app and divide them across data centers and availability zones within datacenters. This might require adding a few of servers if the app is replicated across a very small number of instances, but for apps that already have a significant number of instances to handle the capacity, it's just a matter of rearranging things.
Depending on how quickly new instances of the app can be brought up to, it may be worthwhile to run a bit more capacity so that the remaining instances don't melt down should all the instances in one zone become unavailable.
But AWS has the concept of availability zones that they equate to a data center. AWS refers to an AZ as an "isolated location". It's becoming clear with the S3 outages and this outage that isolation is not as robust as expected so now we see more reference to cross-region replication. But unlike cross-AZ services like S3 or DynamoDB, you need to build your own cross-region replication and failover.
02:10 PM PDT We are investigating network connectivity issues affecting Direct Connect customers using the US-WEST-2 Region.
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Opened at: October 18, 2017 at 3:59:42 PM UTC-5
Network Connectivity
01:59 PM PDT We are investigating Network Connectivity issues in the US-WEST-2 Region.
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Opened at: October 18, 2017 at 3:59:00 PM UTC-5
EC2 VPC network health internet issue
Beginning at Wed, 18 Oct 2017 20:59:00 GMT, some instances are experiencing elevated packet loss between the us-west-2a Availability Zone and the Internet. We are now investigating this issue.
23 comments
[ 3.2 ms ] story [ 46.0 ms ] threadDepending on how quickly new instances of the app can be brought up to, it may be worthwhile to run a bit more capacity so that the remaining instances don't melt down should all the instances in one zone become unavailable.
Direct connect: October 18, 2017 at 4:37:09 PM UTC-5
Internet connectivity: October 18, 2017 at 4:33:29 PM UTC-5
EC2 VPC network health: October 18, 2017 at 4:13:00 PM UTC-5
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Personal Health Dashboard seems like its being udpated faster.
https://phd.aws.amazon.com/
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Opened at: October 18, 2017 at 4:10:19 PM UTC-5
DirectConnect operational issue
02:10 PM PDT We are investigating network connectivity issues affecting Direct Connect customers using the US-WEST-2 Region.
---
Opened at: October 18, 2017 at 3:59:42 PM UTC-5
Network Connectivity
01:59 PM PDT We are investigating Network Connectivity issues in the US-WEST-2 Region.
---
Opened at: October 18, 2017 at 3:59:00 PM UTC-5
EC2 VPC network health internet issue
Beginning at Wed, 18 Oct 2017 20:59:00 GMT, some instances are experiencing elevated packet loss between the us-west-2a Availability Zone and the Internet. We are now investigating this issue.