Server Redundancy

What is Server Redundancy?

Server redundancy involves establishing backup servers to support a primary server. For instance, a website hosted on a single network server without backups lacks redundancy.

A backup server mirrors the primary server, having identical storage, computing capacity, and configurations. If the primary server fails, the backup server can seamlessly take over operations.

Having a redundant server is akin to having a spare tire for your network. In times of downtime, you can replace the flat tire with the spare and continue towards your goal, rather than being stranded on the side of the road. This ensures your business can continue operating smoothly during unexpected events.

Types of Redundant Servers

Server redundancy types refer to various redundant servers that can be deployed on a site. Typically, there are three types of redundant servers that businesses can utilize to safeguard their data and applications.

Domain, front-end, and validation servers

These servers are employed for load balancing to ensure continuous access to services for users. For instance, if the primary server experiences downtime or becomes overloaded, redundant servers can validate user access to the domain for improved load distribution.

Replicated servers

Replicated servers create a duplicate copy of your primary server. In the event of a complete failure of the primary servers due to a disaster, replicated servers can swiftly restore the system to full computing capacity. However, setting up complete proxy servers can be costly.

Disaster recovery servers

Disaster recovery servers act as semi-hot spares designed specifically to store backup data. When disasters occur, they can restore data and processing capabilities to your primary servers, similar to jumpstarting a car.

Benefits of Server Redundancy

No business wants to be at the mercy of a single failed server. Server redundancy offers several advantages to support business continuity.

Reduce Downtime

Downtime can be costly. Redundant servers ensure access to critical data and maintain normal operations when a primary server goes offline due to a disaster, significantly reducing downtime and maximizing uptime.

Maintenance Flexibility

When primary servers require maintenance, backup servers can seamlessly take over. This allows systems to operate without disruption while IT teams address issues.

Enhance Resilience

Server redundancy provides additional resources that can be deployed during disasters or failures, bolstering overall resilience. Many redundant servers include real-time system monitoring, preemptively identifying and addressing potential issues to maintain server health.

Improve Performance

As businesses expand, original servers may struggle to handle peak usage. Deploying redundant servers can alleviate this strain. Multiple redundant servers can be integrated into a cluster, sharing the same IP address and operating as a unified entity. This setup not only enhances performance but also provides cost-effective redundancy as additional servers are added to the cluster.

How to Establish Server Redundancy

If you're considering implementing server redundancy in your current architecture, here are several key considerations to keep in mind:

Building a New Network Infrastructure

Creating server redundancy fundamentally involves constructing a new network infrastructure that replicates the data stored on your primary server. Typically, this setup includes at least one primary server and an identical backup server.

However, merely having a backup server on standby isn't enough. Storing a server in its shipping box in the server room may technically fulfill redundancy requirements, but it doesn't ensure a resilient system. Deployment of the redundant server should be swift to seamlessly take over when the primary server fails, minimizing downtime.

Other Redundant Components

In addition to redundant servers, duplicating other critical infrastructure components is essential to ensure maximum uptime in disaster scenarios.

Backups

Implementing regular backups ensures data is duplicated and stored separately, allowing for quick recovery in case of data loss during disasters. Failure to maintain backups risks permanent data loss, impacting business continuity.

Disk Drives

Redundant disk drives enhance performance by increasing data storage and access capabilities. If a disk drive fails on the primary server, another drive can immediately take over to maintain server operations during single disk failures.

Power Supplies

Deploying redundant power supplies for critical servers ensures operations continue even if the main power supply fails.

Internet Connectivity

Maintaining uninterrupted internet connectivity is crucial for continuous server operation. It's advisable to have connections from different telecom providers to mitigate risks associated with line failures or maintenance downtime.

Server Failover

To enhance server redundancy, many businesses implement server failover solutions. These systems continuously monitor primary servers for potential issues. Upon detecting errors or signs of failure, they automatically redirect network traffic to redundant servers by updating DNS records.

Failover can be automatic or manual. Automatic failover ensures seamless server transitions with minimal downtime but typically involves higher costs. Manual failover involves human intervention to switch to a redundant server, resulting in a brief period of downtime but generally incurs lower operating costs.

Implementing either failover method enhances server redundancy, increases uptime, and mitigates outages. Businesses should carefully weigh the benefits, risks, and costs associated with each method before making a decision.