Is it possible to have ASG as a DR between two AZ? For example, I have 5 instance in AZ1 servicing requests. During the AZ outage, I wanted to spin-up the 5 Instances in AZ2 and serve the request. Is it possible to control the isntance spinning up in AZ2 if only AZ1 Fails ?
You can use AWS AutoScaling across multiple AZ, but only in a specific Region.
"Auto Scaling can work across multiple Availability Zones in an AWS
Region, making it easier to automate increasing and decreasing of
capacity."
If you are trying to have high availability you can use aws global services like AWS CloudFront or AWS Global Accelerator. Example Scenario:
Related
As part of our project we are using AWS RDS postgres service. While creating RDS service AWS mandated to create two subnets from different AZs (ex: us-west-2a and us-west-2b). But we have only one subnet. Is there any way to overcome this problem.
Thanks in advance.
To ensure High Availability, you need to specify subnets in two different Availability Zones (AZs).
Each AZ operates in a different data center. If an AZ fails, the Amazon RDS service will automatically launch a replacement database in a different AZ. Therefore, it requires a minimum of two different AZs to be specfiied.
Why I should configure an AWS ECS Service or an EC2 Instance with two or more Private Subnets from the same VPC? What would be the benefits of doing such thing instead of configuring it within just one Subnet? Would it be because of availability? I've read the documentation but it was not clear about it.
Reference: https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Subnets.html
This is generally to distribute your ECS service across multiple availability zones, allowing your service to maintain high availability.
A subnet is bound to a single AZ, so it is assumed each subnet is in a different AZ.
By splitting across multiple subnets, during an outage load can be shifted to launch containers entirely in other subnets (assuming they're in different AZs).
This is generally encouraged for all services that support multiple availability zones.
More information on Amazon ECS Availability best practices are available from the blog.
I want to test my dynamodb with one availability zone failure.
The basic idea comes to my mind is that find out EC2 instance(s) which dynamodb is running on within an availability zone, and stop or terminated it/them or do something in security group or NACL that related to the EC2 instance(s).
But I am even not found the EC2 instance that running dynamodb in my AWS account.
Any idea is welcome!!!
DynamoDB doesn't run on EC2 instances in your account. Like for example S3 it's a AWS-managed service running on hardware outside of your account. Because of that you can't test partial failures of DynamoDB, because you have no possibility to induce such failures into DynamoDB.
I have configured an AWS auto-scale group with 2 available zones: us-east-1a and us-east-1c . Today, with the issue AWS had on us-east-1a, I noticed that new instances are not created on us-east-1c zone.
Any clues on what I should check on?
Thank you.
Amazon EC2 Auto Scaling can deploy EC2 instances across multiple Availability Zones within one region.
It cannot deploy instances across multiple Availability Zones.
If you wish to implement redundancy across regions, you would need to configure Amazon Route 53 with a health check to route traffic to instances or load balancers in different regions. However, Auto Scaling would continue to operate independently in each region.
I hope you can provide a quick response to my question.
Is it possible to create auto scaling group which spans across regions ? Consider this scenario - Lets say all the availability zones in west are unavailabe. Can we configure auto scaling so that if the instance in US.West are down, create an instance in east zone ?
I dont think it is possible, because we need to specify the region for AWS_AUTO_SCALING_URL while using Command line scripts, which restricts the creation of launch configs, auto scaling group within that region only.
So we can only hope all the AZ's in that region are not down or move to VPC is that right ?
Elastic load balancing and Elastic IP are both region specific, I would assume that auto scaling is region specific and only between the availability zones in that region. The white paper on building fault tolerant applications doesn't explicitly state that you could auto-scale across regions but it does say that you can across zones.
"Auto Scaling can work across multiple Availability Zones in an AWS Region, making it easier to automate increasing and
decreasing of capacity."
I would believe if they supported multi-region, they would explicitly say so.
Thinking about this further, I'm not so sure it's even a good idea to auto-scale across regions. Auto-scale is more geared for a specific tier of your application.
For example, if a region was to go down, you would not want some of your web servers to use services across a slow link to another region (potentially) across the country.
Instead you would want route 53 to route the traffic to an autonomous stack running it's own auto-scaled layers in a separate region.
see this hosting chart everything from ELB down is region specific.
An Auto Scaling group can contain EC2 instances from multiple Availability Zones within the same region. However, an Auto Scaling group can't contain EC2 instances from multiple regions.
Read Note in this AWS Document
EC2 Auto Scaling groups are regional constructs. They can span Availability Zones, but not AWS regions.
PS. AWS Documentation
https://aws.amazon.com/ec2/autoscaling/faqs/