The term ‘High Availability’ refers to the ability of a system to operate continuously (without failing) for an extended period. It is one of the most important benefits your company can get from adopting cloud hosting. This is because the cloud’s capabilities to provide a quick failover of server instances, networks, storage systems, and databases in an event of failure ensure near-continuous availability of applications and data. The infrastructure of these systems is spread across geographically dispersed locations so that they could keep operating without any interruption.
Why High Availability is Important?
Service interruptions and downtime are simply not acceptable in today’s world. For this reason, companies want to have a system that can ensure continuous operation even if something goes wrong.
The implementation of high availability in cloud computing systems is an extremely effective strategy to minimize the impact of these unexpected events. This is because they can recover automatically in case of a component failure as well as a server problem. Hence, high availability systems can fulfill the uptime requirement that is extremely important, especially for mission-critical systems.
Principles for Designing High Availability Systems
The primary goal of high availability is to keep a system operational all the time. Although it is not possible to achieve 100% success, certain measures can be taken to maximize the uptime. The following are three basic guidelines that must be implemented to create a high availability system.
Eliminate Single Points of Failure
A single point of failure is a component that can result in a service interruption if it fails. This means that you should have a backup for all of these components to ensure continuous operation. For example, an application is running on a server (that doesn’t have a backup) and it fails. The application will become unavailable and will stay that way until the problem with the server is resolved. Therefore, it’s imperative to eliminate single points of failure from a system to ensure high availability.
Build Redundancy
Creating a backup for every component of the system is an effective way to counter single points of failure. This means that redundancy should be implemented on each layer of your technology stack. Starting from the servers, every piece of hardware should have a backup and it must be linked together. Similarly, all the applications and software must be installed on both systems to manage the failures. This will ensure that the information from the main system is transferred to the backup without affecting the performance.
Implement Failure Detectability and Failover
Once you have the redundant infrastructure in place, it’s important to know when the system experiences a failure. Also, there should be a mechanism to detect the failures and take appropriate steps for recovery. Therefore, a high availability system must have a failover model that could take care of all these things. In most cases, the top-to-bottom approach is used where the top layer is responsible for any failure in the layer beneath it.
In addition to that, you will need to have a load-balancing mechanism so that the traffic can be diverted to the operational system. This will make sure that the users get an uninterrupted service and that the performance of the system is not compromised.
How Does High Availability Contribute to Data Resilience?
Data resilience is the ability of the data to recover after being compromised. It is done through redundancy and high availability systems to make sure that this response is quick and efficient. Some of the major factors that enable these systems to ensure data resilience are discussed below.
Cloud Datacenter Resiliency
Public cloud service providers maintain discrete demarcations and define data residency boundaries across multiple regions and geographies. These regions and availability zones are designed to help you achieve the resiliency and reliability of your business-critical workloads. These data centers are at physically separate locations and are designed and equipped with independent power. Likewise, they have their independent cooling and networking infrastructure so that they could ensure continuous operation in case of a disaster.
All of these availability zones are connected by a high-performance network. It has extremely low latency and is tolerant to local failures of software and hardware in an event of earthquake, flood, wind power failure.
Load Balancing
This service is responsible for distributing application traffic across various services and guarantees high availability between two regions. It ensures the smooth continuation of services in an event of a crash or a disturbance in one of the regions. In this way, a high availability system ensures maximum potential uptime so that the users can access it at all times.
Cluster Horizontal Scaling (scale-out)
Auto-scale feature scales out the instances impeccably whenever demand increases. Auto-scaling allows you to set alerts and notifications based on your scaling criteria. This is an amazing feature that enables you to manage extra load without shutting down your system.
Application Gateway Routing
When applications are deployed in two regions to achieve high availability, the application gateway routes incoming requests to the primary region. If the primary region becomes unavailable, traffic is routed to the application running in the secondary region. In this way, continuous and uninterrupted availability of the service is provided to the users.
Geo-replication of Databases
Geo-replication lets you create a continuous synchronized readable secondary database for the primary database, in the same or more commonly in a different region. The geo-replication is designed for business continuity and lets you perform quick failover in case of an outage. It also serves as a safe backup of your precious data that can be recovered without making any special effort.
Support and Monitoring
Cloud infrastructure is monitored around the clock (24×7) to detect and solve any issues before they can adversely affect your services. If a problem does arise, cloud engineers are available to handle and solve any technical issue. This means that you won’t have to worry about the technical aspect of your business. Hence, you get the peace of mind to focus on the main objective of your company.
Our Approach
Our experienced team of professionals at IT services has provided high-availability components and services to several businesses and companies. We have a detailed understanding of all the important aspects and features of these systems and use them to fulfill the uptime requirements of our clients. Some of the key features that we consider while designing high availability systems are listed below.
- Location / Availability Zones
- Networking
- Compute Instances deployment
- Load Balancing
- Cluster / Scale-out
- Database read replica
- Monitoring
