According to searchdatacenter.techtarget.com, “High availability (HA) is the ability of a system to operate continuously without failing for a designated period of time.” Meaning HA is the term used to ensure a system meets an agreed-upon operational performance level. Nowadays, through the dependency on digital solutions and transactions even small organizations rely on HA solutions.
High Availability lets your system remain operational over a long period even if some of the components fail. HA refers to such systems that offer a high level of operational performance, usually for a specified period of time. In relation to the example above, an HA system could experience such a problem and continue to operate with minimal downtime or external disturbance in the operations. It allows services with critical importance to be always online and undisturbed, regardless of location or external situation.
For example, during the recent Covid lockdowns in 2020-2021, many organizations and IT departments experienced difficulty finding and utilizing people to service their servers, data centers, etc. And of course, for many businesses being offline could prove to be detrimental to their overall success.
1.What is high availability?
High availability (HA) – as the name suggests – is a term that describes the ability of the system components to continue functioning in a specified time frame. It can be measured relative to fully operational or 100% – in the industry, for example, a popular standard of availability for a product is “five 9s” (99.999%) availability (5.26 minutes downtime per year).
To achieve the status of HA, all experts are unanimous that a product must be well-designed and its segments – well tested before it’s deployed in the field. A significant part of HA systems is, one way or another, developed with the notion of backup and failover processing and data storage and access. This means that all the individual components, which build up such a system must always be present. As a result, all elements are duplicated to evade single points of failure.
If one of the elements fails, the failover process is activated, and it transfers the processing to the redundant component. This method returns everything to normal in just a matter of microseconds. And the higher the percentage of availability to a system, the more open the failover is to the user.
2.What is high availability architecture?
Increasing the components of a system does not automatically turn it into a high-availability system. On the contrary, the greater the system’s complexity, the greater its risk of failure.
Data sharing, applications, and e-commerce websites are just some of the places where you will find almost unanimous utilization of HA clusters.
As mentioned earlier, HA solutions create redundancy within a cluster to eliminate any single point of failure. This includes multiplying network connections with redundant cables, switches, ports. And not just the network, all components need to be redundant to achieve HA, such as storage, compute components, etc. In some cases, you even need geo-distributed clusters.
Modern architectures also use load balancing – it distributes workloads across multiple instances such as a network or a cluster. Thus helps optimize resource usage, maximize performance, minimize response times, and avoid overburdening any device.
3.Main Benefits of HA
3.a Availability & Five 9’s Uptime
The industry benchmark for measuring uptime is the five nines.
This metric can be applied to
- the entire system
- the system processes
- the software running within an infrastructure.
The more 9s an HA system has, the higher its uptime. The aim of a HA system is to provide as little downtime as possible and the framework to continue to provide the desired services.
Uptime is one of the most significant properties of a high-availability device. Moreover, uptime is essential, mainly when a system’s function offers a critical service – for example, air traffic control. In such scenarios, even a millisecond of delay could be the difference between life and death.
If the system encounters a problem – for example, a traffic spike or a rise in resource demand, it should be able to scale to meet those needs on the go. By integrating features like these into the system, the system would adapt rapidly to any changes in the architecture’s processes’ structural functionality.
3.d Handling errors
If an error appears, the system can adjust and compensate while staying up and operating. This form of structure necessitates forethought and contingency planning. One of the essential characteristics of a high availability system is anticipating problems and preparing for them in advance.
4. High availability vs. disaster recovery?
Disaster recovery does exactly what it says – it prepares a detailed plan that helps a system recover quickly after it has experienced a failure. However, why do you need disaster recovery if you have a highly available system?
DR usually is focused on getting back online after a severe crash. HA is focused, however, on failures that are more likely to happen – for example, a failing server. A DR plan could deal with the recovery of an entire region.
5. Possible HA Implementations
One of the methods for achieving HA is by using multiple application servers. If you experience a sudden surge in traffic, your server may shut down, and requests from it can’t be made – which inevitably leads to more downtime. To avoid such scenarios, applications are deployed by using redundant components – across several servers – and if one fails, the rest can take the extra load, allowing for a high fault tolerance.
Another method for achieving HA is by scaling databases, application stacks, etc. HA is perhaps the most widely-used method to save and protect the data of your users. As an organization leader knows, losing such vital information can often be a very costly experience. Application stacks are also a subject to HA; therefore, many modern applications need to be Highly Available for the best user experience.
Finally, HA can be achieved by also spreading the servers across multiple geographical locations. Political events, natural disasters, failures of the electric grid can all lead to a shut down of your servers – even if they are several but clustered in one geographic location. To ensure the safety of the data and complete protection, modern solutions spread their servers worldwide. This further increases their reliability and allows for flexible disaster recovery plans.
6.Why choose LINBIT High Availability?
LINBIT – the creators of DRBD – has over 20 years of experience in storage, high availability systems, and disaster recovery. LINBIT is proud to provide HA services to other notable companies and organizations. Many of them choose LINBIT HA, the enterprise solution built on DRBD, because of the lack of vendor lock-ins – the clients pay only in respect to what they use and are accessible at any moment to switch to other platforms. LINBIT HA can handle databases to file servers, storage targets, and application stacks – while maintaining low TCO.
If you’re interested and want to learn more about how to increase your uptime significantly, click here to learn more on LINBIT HA or request a quote today.