As the demand for server speed and reliability increases, the need to implement a reliable server cluster to ensure maximum performance is paramount. With a tightly integrated cluster of multiple servers working in tandem, you’ll be able to deliver robust services that are resilient, consistent, and provide uninterrupted performance.
Server clusters are key to delivering excellent business service availability while controlling costs. Learn about some of the key benefits that come with using a server cluster.
Server Cluster Benefits and How They Really Work
A server cluster is a group of servers, all linked to the same IP address. They can provide access to files, printers, messages and emails, or database records. Each server in the cluster is called a node, and each node can run independently as it has its own CPU and RAM and independent or shared data storage.
The main advantage of server clustering is better uptime through redundancy. If one node in the cluster, one server, fails, the others are fully capable of taking over almost instantly. User access is essentially uninterrupted, and unless the server cluster is already severely under-resourced, there should not be any performance issues for the expected user load.
Benefits of using server clusters to power mission-critical applications
Server clustering is used in a variety of hosting environments. That is, the benefits of the server cluster are not exclusive to mission-critical applications. However, their main benefit is that they are not subject to a service interruption due to a single server node failure. This is kind of the holy grail for a mission critical application.
Similar benefits can be realized by operating a backup server, either on or off site. However, there is almost always a noticeable service failure while transferring to backup, and the chance of data loss is high, especially when the server is not backed up continuously.
Strategies to ensure maximum performance, reliability, and availability
The main benefits of the server cluster are reliability and availability. However, there are many ways to achieve these two objectives and many strategies to maximize reliability and availability with other factors, especially cost.
Basically, there are two types of server clustering strategies: the traditional strategy and the share nothing strategy.
The traditional server cluster sees multiple redundant server nodes accessing the same shared storage or SAN resource. If a server node fails or experiences downtime, the next node recovers immediately, and as it accesses the same storage, there should be virtually no data loss. However, if the failure occurs on the SAN, there are problems.
The Shared Nothing server cluster views each node as having a completely independent data store, essentially a hard drive. These units are generally synchronized at the block level and are effectively identical from one moment to the next. If a failure occurs anywhere in the cluster, another node can take over its own hard drive entirely.
Protecting clusters against failures and outages
The primary defense that server clustering provides against service interruptions is component redundancy. For example:
Application and service failure
Application or service failures are often the result of critical bugs in the software running the server. Clustering can help when running multiple independent copies of the software.
System and hardware failure
If a physical failure or failure develops, it will generally only affect one node in the cluster. The other node or nodes can take over.
Site failures typically occur throughout the data center, whether from power outages, natural disasters, or human error. Clustering could only protect against a site failure if one or more of the cluster nodes were located on a different site, which can be expensive and inefficient, but is quite feasible.
Security Considerations When Deploying a Server Cluster
With all the server cluster benefits on offer, it’s easy to forget that all servers are potentially vulnerable. You need to address the same security concerns when setting up a clustered server as you do with any other:
Different types of server clusters
As we delve deeper into what server clusters are, it’s time to explore each of the main types of clustered server arrays.
Basic cluster storage
These are your bread and butter cluster storage solutions without any of the bells and whistles. They work perfectly fine for most purposes and are inexpensive.
High Availability (HA) Server Clusters
These are usually shared storage clusters and can be made up of virtual machines running on a single host. They maximize uptime, but may compromise reliability slightly.
Load Balancing Clusters
These clusters use a load balancer or cluster switch to, as you might imagine, load balance incoming requests across multiple nodes running at the same time. Optimize service speed rather than uptime or reliability.
High Performance Clustered Storage (HPC)
An HPC cluster uses top-of-the-line hardware on each node of a large cluster and the fastest interconnect available. It maximizes performance, but by doing it primarily at the hardware level, it generally doesn’t compromise reliability or availability. Often all three are taller than standard clusters.
Cost savings and other benefits of server clustering
One of the most important benefits of server clustering on a practical level is the reduction in IT costs that customers typically realize. Less downtime simply costs less in the end, even with a more expensive setup.
Other benefits include greater flexibility, scalability, performance, and availability, as well as a more easily customizable server infrastructure.
Server clustering is a very effective strategy to ensure that your most critical data resources provide all the uptime you need. There are several ways to modify the cluster architecture or hardware to focus on specific benefits, but almost all server cluster strategies offer improved performance, uptime, and reliability. It’s a matter of choosing the best of several good options, a type of problem that the IT industry sees very little.