Downtime. A phrase that strikes fear into the heart of any IT professional. Downtime opens the door to a maze of extra maintenance hours and impatient managers.
Growing businesses demand a reliable infrastructure that minimizes downtime and single points of failure, making terms like “high availability” and “failover” more popular than ever.
But beyond being buzzwords, what are the real implications for managers and business owners?
Keep reading to learn everything about failover!
In the IT industry, the term availability generally refers to the amount of time a service is expected to be operational. But do you know what makes an infrastructure truly highly available?
The Harvard Research Group categorizes availability environments into five levels, from AE0 to AE4.
AE0 represents a conventional system, with occasional interruptions or potential data loss.
An AE4 environment, on the other hand, offers 24/7 operation with no data loss, and any failures are completely transparent to the user.
While there is no official industry standard for high availability, Harvard’s classifications help provide a general framework for understanding availability. High availability typically falls within AE2 and AE3 classifications.
Availability is measured as a percentage. An availability of 99% means there’s a 1% chance of downtime. Over a 365-day year, that equates to 3.65 days of downtime.
Most modern systems offer around 99.99% or 99.999% availability. Technically, 100% availability doesn’t exist, but many high-availability systems have minimal downtime compared to outdated or unreliable ones.
High availability is made possible through fault tolerance and redundancy. Fault tolerance is defined as a capability that, in the event of a component failure, triggers a backup process or component to take over. This results in little or no service interruption.
Fault tolerance is typically achieved through a combination of software and hardware. Its primary goal is to ensure that services remain available to users at all times.
When deploying a high availability system, part of achieving strong fault tolerance involves identifying and eliminating single points of failure (SPOFs). A SPOF is any system component that, if it fails, disrupts the entire system, making it unreliable or unavailable.
Redundancy essentially acts as a backup while also contributing to the system’s overall availability. It can be passive, where standby components are only activated in case of failure, or active, where all components operate simultaneously and share the load.
It involves two identical processing systems, but only one output is used so there is no redundancy at the endpoint. Both components have equal capabilities, so if one device fails, there is no change in performance or functionality when switching from one to the other.
It allows one device to process the task while the other remains inactive. The second device stays on standby, ready to be used in case of a failure. This setup requires a switching component that can redirect input and output channels during a failure event.
Redundancy mitigates SPOFs by providing an extra layer of protection if a single hardware component fails. Without redundancy, a single hardware failure can be catastrophic to a machine.
What Does High Availability Look Like in Action? For the purposes of this article, we’ll focus on high availability in relation to physical servers, as opposed to a virtualized environment. On-site high availability (server availability) is primarily used to ensure business continuity. Large volumes of traffic can cause network delays and lead to downtime.
To mitigate this, companies implement the principle of redundancy, typically deploying two servers in a single location. At SmartFile, our FileHub solution works the same way. The two servers run in an active-active redundancy setup—both devices operate in coordination, sharing the traffic and processing load. This relieves the burden from a single device, improving network speed and efficiency, and resulting in minimal or no downtime.
High availability should be applied whenever a critical business process is involved. For instance, consider a construction company that uses a file server to store all of its project documents. Internally, this system is the backbone of the organization. Externally, subcontractors and remote employees need timely access to those files. Downtime leads to delays—and directly affects revenue.
A software company using SmartFile to collect log files or push software updates to clients also depends heavily on availability. If a client can’t upload a log file or a support technician can’t download it, the resolution of issues is delayed. Slower problem-solving harms business relationships, and a loss of trust can mean losing a client.
Not every company needs high availability, but for some, it’s absolutely essential. Ultimately, high availability is usually implemented as a critical part of an organization’s broader IT strategy.
There are two ways a contingency plan can be triggered, and the device switch can occur. Both deliver the same desired result, and as a result, the term failover is used to cover both scenarios.
Technically, when the switch is automatic, it is referred to as failover. If the switch requires human intervention (manual device switching or approval before a contingency plan is executed), it is known as switchover.
There are two ways a contingency plan can be triggered and the device switch can occur. Both deliver the same desired result, and as a result, the term failover is used to cover both scenarios.
Technically, when the switch is automatic, it is referred to as failover. If the switch requires human intervention (manual device switching or approval before a contingency plan is executed), it is known as switchover.
Failover can be triggered in several ways. If the backup device detects a link failure from the primary, a failover occurs. Failover can also be triggered by an anomaly in the heart of the device. The heartbeat is the detection mechanism that communicates between the primary and backup devices. If the primary device stops responding to the heartbeat, the backup device takes over.
Here are the main advantages of using failover in your company:
By incorporating failover into both hardware and software, businesses ensure that critical services remain available, even if a component fails, offering greater resilience and reliability in their IT infrastructure.
To avoid losses, many companies use failover to ensure their activities are not interrupted. This high availability allows productivity to remain unaffected and ensures higher customer satisfaction. By implementing failover systems, businesses can maintain continuous service even during failures, preventing downtime and providing a seamless experience for both employees and customers.
Failover can be applied to a wide range of hardware, from routers to physical servers. In software, it is also used to provide redundancy to programs, such as databases and virtual servers. By integrating failover mechanisms, both hardware and software systems become more resilient, ensuring uninterrupted service even during failures. This versatility makes failover a crucial component in maintaining high availability and reliability across various types of infrastructure.
To avoid losses, many companies use failover to ensure their activities are not interrupted. This high availability allows productivity to remain unaffected and helps keep customers satisfied.
Performing maintenance on a system can delay various processes and even halt some business activities. However, with failover, this is not necessary, as while maintenance is being carried out on one system, the other continues to operate normally.
Failover is typically used as a disaster recovery strategy. Two devices are deployed in strategically chosen, geographically diversified locations, usually far from the original office. This way, if a natural disaster or emergency makes the primary device at the original location unusable, the second device is safely away from the damage.
At SmartFile, we implement geographically distributed, capable servers that utilize active-passive redundancy. When an anomaly in the primary system’s operational pattern is detected, the workflow can be redirected to the secondary device. For businesses that need to adapt to regions prone to hurricanes or tornadoes, failover is a blessing. Downtime and revenue loss are not options, and failover ensures the business continues to run smoothly.
Deciding whether your company needs high availability, failover, or both is challenging. Ultimately, the decision should complement your organizational IT strategy with a specific focus on the business process being addressed.
Larger companies are inherently focused on business continuity due to the broader impact. If disaster recovery is the goal, failover is your best option. High availability and failover are more than just technological buzzwords. They provide a more stable and fortified network.
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