Components - such as drives, racks, or servers - are redundant.
Systems - such as disk networks or cloud computing networks - are fault tolerant.
In other words, redundant means having more than one thing in case the first instance fails. Having two disks on the same system that are regularly copied causes them to be redundant because if one fails, the other can remove the game. If the entire system fails, however, both disks are unnecessary. It is the role of fault tolerance to maintain the entire system, even if parts of the system fail. So how does this apply to EC2 and the Amazon cloud?
FIG 1.1 AWS TRAINING IN CLOUD
Save Grace For many businesses, the cloud works for both home and flexible DR services in the event of local system failures. But what happens when the cloud itself decreases? Like all cloud vendors, Amazon has experienced malfunctions due to bad weather, power outages, and other disasters; while the company promises 99.95 percent of operating time to its computing instances, this still accounts for about four hours off per year. Using Amazon as a DR solution is now possible and recommended, but it is not perfect.
To address this problem, EC2 comes with a number of tools that can help businesses increase their overall redundancy and overall fault tolerance. Restoring Redundancy How do companies address the issue of redundancy in their EC2 instances? Starts with availability zones (AZ).
These areas are divided by region - which means that if you are on the west coast of the United States, you will have the choice between several areas along the coast that are independently fed and cooled and have their own networks and architectures. safety. AZs are isolated from failures in other areas of the group, making it a simple form of redundancy. By replicating your EC2 instance to multiple AZs, you greatly reduce the risk of failure or total failure. Note that bandwidth at zone boundaries costs $ 0.01 / GB, a fraction of the cost of Internet traffic in general, but it is important to consider when calculating cloud costs.
It is also important to remember that information transfer has an upper limit limited by the speed of light, which means that if you use two geographically remote AZs to host your EC2 instances, you may have some latency in case of failure.
VIDEO 1.1 AWS TUTORIAL
Connection Failure Tolerance As the AWS reference architecture for fault tolerance and high availability, while top-level services such as Amazon Simple Storage Service (S3), Amazon SimpleDB, Simple Queue Service (SQS), and Elastic Load Balance ELB) is intrinsically defective, tolerant, the EC2 instances are equipped with a number of tools that must be used properly to achieve the general fault tolerance.
For example, using ELB can help migrate workloads to unsuccessful EC2 instances and avoid wasting resources by creating an Auto Scaling group, as well as an existing ELB load balancer, automatically terminates for "unhealthy" cases and launches others. It is also essential to use elastic IP addresses that are public IP addresses that can be mapped to any EC2 instance in the same region because they are associated with your AWS account and not the same instance itself.
In the event of a sudden failure of EC2, the elastic IP allows you to move network requests and traffic in less than two minutes. It is also advisable to use Snapshots in combination with S3: taking point-to-time snapshots of your EC2 instance, saving them in S3 and replicating them in multiple AZs, you can reduce the impact of unexpected or emerging crashes. Essential workloads have a place in Amazon's EC2 offering. However, to ensure the high availability required by these workloads, the redundant and fault-tolerant tools included in any elastic computing cloud instances should be used.