Architectural Reliability Considerations

Application reliability is an essential aspect of architecture design and vital for any business to be successful.

Reliability means the ability of the system to recover from failure. It’s about making your application fault-tolerant and able to recover from any infrastructure or server failure without impacting the customer experience. Your system should be prepared to handle any situation that could cause disruption.

As all kinds of businesses are now online, high availability has also become a mandatory criterion for online applications. Users want to browse your application anytime and complete tasks such as shopping and banking at their convenience. In this chapter, you will learn various design principles to make your solution reliable. When assessing reliability, you need to consider every component of the architecture. You will understand how to choose the right technology to ensure your architecture’s reliability...

Design principles for architectural reliability

Reliability and high availability (HA) are foundational pillars for ensuring that applications and infrastructure can meet user demands without interruption. Reliability focuses on the system’s ability to operate correctly under specific conditions and for a particular period.

It involves designing systems to contain and manage failures in the smallest scope possible, minimizing the impact on overall operations. This approach requires a comprehensive understanding of potential failure modes and implementing targeted mitigation strategies to either prevent these failures or recover gracefully from them.

HA, discussed in detail in Chapter 2, is closely related to reliability but with an emphasis on ensuring that services remain accessible at all times. HA strategies involve creating redundant systems and components to eliminate single points of failure, thereby allowing for seamless failover in case of an outage. The goal...

Technology selection for architectural reliability

Application reliability often looks at the availability of the application to serve users. Several factors go into making your application highly available. However, fault tolerance refers to the built-in redundancy of an application’s components. Your application may be highly available but not be 100% fault-tolerant. For example, if your application needs four servers to handle the user request, you divide them between two data centers for HA.

If one site goes down, your system is still highly available at 50% capacity, but it may impact user performance expectations. However, if you create equal redundancy in both sites with four servers each, your application will not only be highly available but will also be 100% fault-tolerant.

Suppose your application is not 100% fault-tolerant. In that case, you want to add automated scalability, defining how your application’s infrastructure will respond to increased...

Improving reliability with the cloud

In previous sections, you have seen examples of a cloud workload for the DR site. Many organizations have started to choose the cloud for DR sites to improve application reliability. Also, cloud marketplaces from major providers like AWS, Azure, and GCP offer a wide range of third-party solutions that can be integrated into DR planning and execution. These offerings typically include tools for backup and replication, orchestration, monitoring, and security.

The cloud provides data centers that are available across geographic locations at your fingertips. You can create a reliable site on another continent without any hassle. With the cloud, you can easily create and track the availability of your infrastructure, such as backups and machine images.

In the cloud, easy monitoring and tracking help make sure your application is highly available as per the business-defined SLA. The cloud gives you fine control over IT resources, cost, and handling...

Summary

In this chapter, you learned about various principles to make your system reliable. These principles include making your system self-healing by applying automation rules and reducing the impact in the event of failure by designing a distributed system where the workload spans multiple resources.

Overall system reliability heavily depends on your system’s availability and ability to recover from disaster events. You learned about synchronous and asynchronous data replication types and how they affect your system reliability. You learned about various data replication methods, including array-based, network-based, host-based, and hypervisor-based methods. Each replication method has its pros and cons. There are multiple vendors’ products available to achieve the desired data replication.

You learned about various disaster planning methods depending on the organization’s needs and the RTO and RPO. You learned about the backup and restore method, which...