Understanding The Importance Of Redundant Systems In Data Centers

Reliability is a major selling point for data centers. This means that reputable data center operators make it a top priority. Implementing redundant infrastructure and systems along with robust failover systems is key to ensuring high levels of reliability. Here is a quick guide to what you need to know.

Types of redundancy in data centers

There are five main types of redundancy in data centers. These are power, cooling, network, equipment, and data. Here is a closer look at each of these types of redundancy.

Power redundancy

Typically, data centers employ multiple layers of redundancy, including Uninterruptible Power Supplies (UPS), diesel generators, and Power Distribution Units (PDUs).

UPS systems provide immediate backup power during brief outages or while generators come online. Diesel generators serve as a secondary power source during prolonged outages or when the primary power grid fails.

Power Distribution Units manage power distribution within the data center, ensuring efficient utilization of available power and providing redundancy at the distribution level.

Cooling redundancy

Redundant cooling systems typically consist of multiple air conditioning units, chillers, and cooling towers. These systems work in parallel to regulate the temperature and humidity levels within the data center environment.

Network redundancy

Redundant network components include multiple Internet Service Providers (ISPs), network switches, routers, and network paths. Redundancy at various levels of the network architecture allows for automatic rerouting of traffic in case of link failures or equipment malfunctions, maintaining seamless connectivity and minimizing service disruptions.

Equipment redundancy

Redundant equipment includes server clusters, hot-swappable components (such as power supplies, fans, and hard drives), and redundant cooling systems. In the event of hardware failure or maintenance activities, redundant equipment can seamlessly take over operations without impacting service availability or performance.

Data redundancy

This involves the duplication of data across multiple storage devices or locations to ensure data availability and integrity in case of storage system failures or data corruption. Redundant data storage methods include RAID (Redundant Array of Independent Disks), cloud-based backups, and offsite data replication.

Implementing failover systems

Failover systems can be manual or automatic. These systems may be used individually or together. Here is a comparison of the two options.

Manual systems

Manual failover provides greater control over the failover process. It allows administrators to assess the situation before executing failover procedures and to customize those procedures based on specific requirements or conditions. Manual failover also tends to be more cost-effective for smaller environments or less critical systems that do not require instantaneous failover capabilities.

On the minus side, however, manual failover systems typically have longer response times compared to automated systems and are more prone to human error. Both of these issues can be exacerbated if there is a shortage of experienced staff when the issue occurs.

Automated systems

Automated failover processes can respond to failures almost instantaneously and are not vulnerable to human error. Moreover, they can easily scale to accommodate growing infrastructure and workload demands.

On the minus side, they can be complex to set up. This alone can make them too expensive for some environments. Furthermore, automated failover processes are not 100% reliable. In particular, they are at risk of generating false positives and triggering failovers unnecessarily.

Examples of technologies used in automated failover

Here is an overview of five key technologies used in automated failover.

Heartbeat monitoring: Heartbeat monitoring involves the continuous exchange of signals or messages between primary and redundant systems within a failover cluster. If the primary system stops sending heartbeats or exhibits abnormal behavior, the redundant system detects the failure and initiates failover procedures.

Cluster management software: Cluster management software orchestrates the operation of redundant resources within a failover cluster, such as servers, storage devices, and networking equipment. These software solutions monitor the health and status of cluster nodes, manage resource allocation, and automatically redistribute workloads in response to failures or load imbalances.

Virtual IP address failover: Virtual IP address failover involves assigning a single virtual IP address to a group of redundant servers or systems within a failover cluster. A monitoring system continuously checks the health and availability of primary servers, and in the event of a failure, dynamically reassigns the virtual IP address to a standby server. This technology ensures seamless failover without requiring changes to client configurations or network settings.

Database replication: Database replication involves the process of copying and synchronizing data between primary and secondary database instances in real-time or near-real-time. In a failover scenario, if the primary database becomes unavailable due to hardware failure or maintenance, the secondary database takes over seamlessly without data loss.

Application load balancers (ALBs): Application Load Balancers distribute incoming network traffic across multiple backend servers or instances to ensure optimal resource utilization and high availability of applications. In automated failover scenarios, ALBs continuously monitor the health and performance of backend servers and automatically route traffic away from unhealthy or failed servers to healthy ones.