As the demand for server speed and reliability increases, the need to implement reliable server clusters to ensure maximum performance becomes paramount. A tightly integrated cluster of multiple servers working in tandem allows us to deliver robust services that are resilient, consistent and deliver uninterrupted performance.
Server clusters are key to providing superior business service availability while controlling costs at the same time. Learn some of the key benefits of using server clusters.
The Benefits of Server Clusters and How They Actually Work
A server cluster is a group of servers all associated with the same IP address. These may provide access to files, printers, messages and emails, or database records. Each server on the cluster is called a node, and each node has its own CPU and RAM, and independent or shared data storage, so it can run independently.
A key benefit of server clustering is increased uptime through redundancy. If he in the cluster fails one node (one server), the other nodes can recover slack almost instantly. User access is essentially uninterrupted and should not cause any performance issues for expected user loads unless the server cluster is already severely under-resourced.
Benefits of using server clusters to power mission-critical applications
Server clustering is used in a variety of hosting environments. In other words, the benefits of server clusters are not limited to mission-critical applications. However, its main advantage is that it is immune to service disruption due to failure of a single server node. This is kind of the holy grail for mission-critical applications.
Operating a backup server onsite or offsite provides similar benefits. However, most likely there will be a noticeable failure of service during the transfer to backup, and the potential for data loss is high, especially if the server is often not continuously backed up.
Strategies to ensure maximum performance, reliability and availability
The main advantages of server clusters are reliability and availability. However, there are many ways to achieve these two goals, and many strategies for maximizing reliability and availability over other factors, especially cost.
There are basically two types of server clustering strategies: traditional strategies and shared-nothing strategies.
In traditional server clustering, multiple redundant server nodes access the same shared storage or SAN resources. In the event of a server node failure or downtime, the next node will quickly recover and access the same storage, resulting in essentially zero data loss. However, problems arise when the SAN fails.
Shared-nothing server clustering assumes that each node has a completely independent data store (essentially a hard drive). These drives are typically synchronized at the block level and are virtually identical from moment to moment. In the event of a failure anywhere in the cluster, another node can completely take over that hard drive.
Protecting your cluster against failures and outages
The core defense that server clustering provides against service outages is component redundancy. for example:
Failure of applications and services
Application or service failures are often caused by serious errors in the software that the server is running. Clustering helps by running multiple independent copies of software.
System and hardware failure
A physical failure or outage usually affects only one node of the cluster. Other nodes can take over.
Site failures typically occur across data centers due to power outages, natural disasters, human error, etc. Clustering can protect against site failures only if one or more nodes of the cluster are located on different sites. This is expensive and inefficient, but quite feasible.
Security considerations when deploying server clusters
With all the benefits of a server cluster, it’s easy to forget that all servers are potentially vulnerable. When setting up a clustered server, you have to deal with the same security issues as you would any other server.
- Use a proper firewall.
- Keep your OS up to date.
- Move data securely to and from your cluster.
- Use strong authentication procedures.
- Physically secure your server.
- Consider encrypting your file system.
Different types of server clusters
Let’s dig deeper into what a server cluster is and examine each of the major types of clustered server deployments.
Basic clustered storage
These are basic clustered storage solutions with no additional features. Works perfectly for most purposes and is low cost.
High availability (HA) server cluster
These are typically shared storage clusters and may consist of virtual machines running on a single host. Maximizes uptime, but may compromise reliability slightly.
load balancing cluster
These clusters use, as you might guess, a load balancer or cluster switch to load balance incoming requests across multiple nodes running simultaneously. Optimize service speed, not uptime or reliability.
High performance clustered (HPC) storage
HPC clusters use top-of-the-line hardware in each node of large clusters and the fastest interconnects available. This maximizes performance, but since it’s done primarily at the hardware level, it usually doesn’t compromise reliability or availability. All three are often higher than the standard cluster.
Cost savings and other benefits of server clustering
One of the most important benefits of server clusters on a practical level is the reduction in IT costs that customers typically experience. Less downtime ultimately costs less, even for expensive setups.
Other benefits include greater flexibility, scalability, performance, availability, and easier customization of your server infrastructure.
Server clustering is a highly effective strategy for ensuring that your most mission-critical data resources can provide all the uptime they need. There are ways to tune your cluster architecture or hardware to focus on a particular advantage, but almost all server clustering strategies improve performance, uptime, and reliability. It’s a question of choosing the best among several good alternatives, but it’s the type of problem that’s too neglected in the IT industry.