High availability or HA is the ability of systems to perform operations continuously without failure for a set time. Read on to know more.
High Availability systems are used in situations and industries where systems have to remain operational, no matter what. High-availability scenarios in the real world include military control, healthcare systems, autonomous vehicles, and industrial systems. Stakes are high for such procedures as they have people's lives depending on them.
However, what exactly is high availability? How do we define it? Here is a look.
What is High Availability?
High availability or HA is the ability of systems to perform operations continuously without failure for a set time. HA functions in ensuring that systems meet a predetermined performance level in their operations. They must be well crafted and undergo thorough testing before usage. Implementing high availability systems requires all components to meet desired availability standards. Data backup and failover capabilities play essential roles in ensuring HA systems meet their availability goals. System designers also have to provide data access and storage technology.
Designing HA Systems
Three principles are used when designing high availability systems:
- Single points of failure - a component that can make the whole system fail if a failure happens. If an enterprise has one server to run the application and falls, the application goes unavailable. Hence, the server becomes a single point of failure.
- Failure detectability - systems must have built-in automation to detect and handle inevitable failures. There should also be built-in mechanisms to avoid common failures.
- Reliable crossover - Building redundancy into HA systems enables a backup to take over in case of failure. In such cases, it is necessary to ensure a reliable crossover.
The Role of Load Balancers
Load balancing becomes necessary in ensuring high availability when many users access a system. Load balancing is capable of automatically distributing workloads to system resources. Load balancers decide which system resource can efficiently handle what workload. Multiple load balancers ensure no one resource takes all the load.
The servers in high availability systems are organized in a tiered architecture (in clusters) to respond to load balancer requests. If any server in the cluster fails, a redundant server in another group handles the designated workload. With complex systems, it gets even more complicated to ensure high availability due to the higher number of points of failure.
