High availability refers to the component or system that performs continuously without failure for a desirable length of time. In computing terms, availability is referred to the time when a service is available, as well as the time needed by a system to respond to a query made by a user. Therefore, high availability is the ability of a system to continuously perform for a long length of time. Or you can say that HA refers to the availability of resources in a computer system, especially when failures occur in the system.
Availability is defined as “100% operations” or “never failing.” However, in IT, a widely-held but challenging to achieve a standard of availability for a system or product is known as “five 9s” (99.999 per cent) availability. High availability is a network standard that is designed to reduce downtime. Given the ever-increasing demand for dependable infrastructures designed to serve critical systems, high availability has become more important than ever. While handling ever-increasing system load is a common issue, fluctuating downtime and avoiding single points of failure are just as critical. High availability is a quality of infrastructure design at a scale that takes care of these latter concerns.
HOW HIGH AVAILABILITY IS MEASURED?
Availability measurement is vulnerable to some degree of interpretation. Equipment that has been running 365 days in a non-leap year might have been plagued by a network failure that continued for 9 hours during a peak usage period; the user community will find the system as unavailable, where the system administrator will claim 100% uptime.
However, according to the legal definition of availability, the system will be nearly 99.9% available. Also, systems with performance issues are often considered partially or entirely unavailable by users, even when the systems are in operation. Likewise, unavailability of select application functions might not be noticed by administrators. Availability must be determined with comprehensive tools that are themselves highly available. In the case of having a lack of tools, systems can be better monitored by users themselves. Coming to the method of measuring high availability, the total duration of the uptime of the system is checked. For example, if system availability is 99 per cent, it indicates that the system remains in operation for 8672.4 hours throughout the year because the total hours in a year are 8760.
The following formula is used to calculate the total availability, and availability can be enhanced using high availability techniques to boost MTTF and decrease MTTR.MTBF stands for the Mean Time Between Failures and shows the estimated time between two frequent failures within a process or a component, which can be repairable.MTTF means mean time to failure and is the total estimated time of a system. It is often beyond repair.
Mean time to repair or replace or MTTR is the average estimated time to
Repair failed equipment or the total replacement time of a failed component.
Thus, many administrators use this formula to measure availability:
Availability = MTTF / (MTTF + MTTR)
Benefits of High Availability
So you must have understood that high availability ensures maximum uptime and eliminates the risk of failure. This system can offer any kind of bandwidth required. Network traffic is monitored and all the system elements are linked to the monitoring tools.
Here we will walk through some key benefits of high availability.
Protection from Downtime:
If one business-critical server collapses, it will affect every server that connects with it. Downtime leads to the loss of nearly $896,000 per week for a company with 10,000 employees. According to one report, over half of Fortune 500 companies experience a minimum of 1.6 hours of downtime every week. The direct losses leave a heavy risk of losing customer trust. Any form of unexpected application downtime can hinder business success regardless of the role that a specific application plays within the business.
This is where HA comes in. In case of the failure of one server, HA lets you seamlessly transfer operations over to a host server. This way, employees can get their work done, the network can still be maintained and downtime can’t hamper business productivity.
Minimizes the Risk of Losing Revenue:
A failed server can affect productivity as it is challenging to make the sales, and existing clients cannot be helped. Therefore, such problems bother both businesses and their clients. The quicker you get your server back to work, the faster you can handle your business as usual. With partial failover solutions, the operations can be transferred to the host server and continue functioning as if nothing happened to the original server. This needs special expertise in layer 2 communications, which lets data from your business to travel through an encrypted and scalable network configuration to arrive security at the host server.
Ease of Maintenance:
Unpredictable downtime from an incident isn’t the only type of concern that businesses encounter. Hardware and software updates or upgrades are other scenarios where enterprises can face devastating downtime. With HA solutions, this risk can be reduced. Companies can plan to restore their server to the host site, and operate production there while their in-house operations are being adjusted. Therefore, with HA, companies don’t have to be discouraged from making important improvements. You can still make changes to your IT ecosystems.
If your production site is required to be available 24/7, you can turn to HA for getting flexible solutions. Partial failover of individual servers within a layer 2 networking strategy enables the communication between multiple interfaces. The failover site can be seamlessly switched off and transport any changes that arose at the production servers while the main site went offline unless the main production site gets up and running.
Improves Agility and Resilience:
While DR solutions are important, they eat up a large amount of time to coordinate. With HA solutions, it takes only moments to switch over to the failover centre and operate production from there. It’s all customized to your requirements, whether you are looking to update your data within minutes or seconds. The data replication can be personalized, so the version that you’re using at the host site is almost similar to the version of the server that fails. Therefore, HA lets you get the resistance of any effect on your normal business operations; the transition to the host server is smooth, and can be done within seconds. Read Here are some positive aspects of High Availability System.
And What Should You Be Aware Of…
High availability might not be beneficial in some cases. Keep in mind that certain issues occur when you implement an HA system. Good thing is that you can overcome these concerns with the proper planning. The first downside is with local disaster recovery solutions. When the physical site fails, it leads to the destruction of the backup systems as well as the production units.
Here is a solution.
- Make sure to replicate data off-site and or by removing tape backup media to off-site storage units. Such steps will help you overcome minor data Centre disasters.
- The second disadvantage with HA is that failover solutions of any kind are more complicated than DR solutions. Therefore, you need to configure additional server systems to back up for one or more production unit, although some systems are less likely to support many-to-one failover.
- While it is easy to resolve this concern, you shouldn’t ignore it. Be prepared for the execution with training and other things to get over the learning curve.
Key Elements to Get High Availability System for Your Business
The idea of a high availability system is evolved from the necessity of keeping the equipment up and running even if the worst occurs. That requires continuous operation with multiple alternative connections and no downtime. It’s not possible to keep a network up and running in all conditions. Eventually, some will event will lead to a stoppage, but high availability system aims to get back up as fast as possible, automating the process to do things quicker than a technician can.
High availability architecture is an intentional network design that ensures redundancy, dealing with failure. High availability architecture should be incorporated with online backup and emergency recovery. It also requires you to ponder over planning ahead and for emergencies.
Here are some of the key elements you can incorporate to achieve high availability.
It is an ideal way to deal with a transaction failure. In such scenarios, cloud-aware applications can be deployed to intelligently route transactions to a secondary service point. A failed transaction query will automatically be transferred to the second working location.
Network IP Management:
Network IP Management lets a published service IP to move between equipment at the time of downtime. This is termed as a self-healing process, where two servers overlook one another. If the first server fails, the second server is likely to take on its role.
A well-executed monitoring system not only provides insight into an application and its existing function, but it also overlooks error-rates that exceed a predefined verge. For example, an online shopping site can create monitoring on a payment gateway so that if credit card transactions go beyond a 20% failure rate, their Network Operations Center (NOC) automatically gets an alert and activate self-healing.
In the event of hardware failure, assets can be redeployed to a secondary location in minutes. Data replication and resource availability are present in the secondary location, and the timely deployment of the entire application infrastructure is measured within minutes. When executed properly, multi-site configurations let a company reinstall their entire asset in a new data Centre. A multi-site configuration will benefit the businesses that can’t afford downtime in their application infrastructure. In this scenario, the additional site would be completely data Centre that accommodates an independent copy of the primary site infrastructure. Depending on the configuration of the site application, the additional site can either be in an active configuration that takes a portion of the incoming traffic, or a primary failover site that will not serve traffic, but remains ideal while continuously replicating information from the primary. For more information about the topic read out this Informational content.
Best Practices to Achieve High Availability:
Incorporate Multiple Application Servers:
When servers become congested, they are likely to get slow or even worse, crash. Installing applications over several servers will keep apps up and running continuously and minimize downtime.
Don’t keep all your eggs in one basket. This saying is relevant in high availability. After all, another server can take on the role if one server fails. Databases and information should be scaled around the multiple servers. Moreover, each server should have a backup option.
Important network servers shouldn’t be placed in the same location (for example, one workplace). Organizations should invest in various physical server locations. Having a backup server a few miles away can be really useful if a problem occurs in one location.
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