Linux Clustering

What is Linux Clustering?

A high availability Linux cluster is a group of Linux computers or nodes, storage devices that work together and are managed as a single system. In a traditional clustering configuration, two nodes are connected to shared storage (typically a SAN). With Linux clustering, an application is run on one node, and clustering software is used to monitor its operation. If the software detects an issue, it moves operation of the application to the secondary node in a process called failover. Since the secondary node shares storage with the primary, operation can continue quickly, meeting very short (seconds to minutes) recovery time and recovery point objectives.

Linux Open Source High Availability Clustering

Some Linux operating system vendors offer clustering software, such as SUSE Linux HAE; Red Hat Enterprise Linux (RHEL); and Oracle Real Application Clusters (RAC).

While they allow you to create a failover cluster, they present a variety of challenges. First, choosing which software to use for each component of the HA configuration, which at a minimum, must include three related capabilities: data replication, server clustering and a resource manager with a heartbeat monitor. With SUSE and Red Hat, you are also locked into the OS. If you want to use other less expensive or free OS versions, such as CentOS or Oracle Enterprise Linux (OEL), you will need to buy a separate HA solution.

Whichever you choose, creating a Linux clustering solution with open source software for high availability is a “Do-It-Yourself” (DIY) project, that is highly manual and prone to human error.

Linux open-source HA extensions require a high degree of technical skill, creating complexity and reliability issues that challenge most operators.

SUSE Linux Enterprise Server and Red Hat Enterprise Linux both solutions offer both a SAN and SANless environment but require that a replication software called DRBD be installed and configured in the OS to support data replication in the SANless environment. Unfortunately, this requires heavy custom scripting, which can take a long time to test and validate and requires retesting when any updates are made to the environment. Since these companies are operating system companies first and foremost, their support is geared towards operating system-level issues and often there is little to no HA expertise to help a customer with their issues.

Oracle RAC is a high availability solution, but it is primarily architected for the database management tier. This means you will need a different HA solution for those components that do the monitoring, management, and recovery of your application tiers. Oracle RAC is also very expensive – requiring you to upgrade to Oracle Enterprise Edition in addition to paying for the RAC option – typically hundreds of thousands of dollars – when compared to other Linux clustering solutions, such as SIOS Protection Suite.

SIOS Protection Suite for Linux Clustering

The SIOS Protection Suite for Linux provides a tightly integrated combination of high availability failover clustering, continuous application monitoring, data replication, and configurable recovery policies, protecting your business-critical applications from downtime and disasters. While SIOS Protection Suite can operate in a SAN environment to support a traditional HA hardware-based cluster, the architecture takes a shared-nothing approach to server clustering allowing it to run SANless. It delivers a robust, versatile and easily configurable solution with automatic and manual failover/failback recovery policies for a wide variety of applications.

SIOS Protection Suite for Linux includes:

• SIOS LifeKeeper, which provides flexible failover clustering software that monitors the entire application stack
• SIOS DataKeeper, which provides fast, efficient host-based, block-level data replication for mirroring local storage in a SANless cluster configuration or replicating to remote locations or cloud for disaster recovery
• Multiple Application Recovery Kits (ARKs), with automated configuration and validation tools built into the product to protect your business-critical applications and data from downtime and disasters.

It is the SIOS’ team’s depth of knowledge in application recovery and the solution’s automation of application monitoring and recovery that makes it easier to use and a better, less expensive choice when compared to the Linux clustering solutions offered SUSE, Red Hat, and Oracle.

In addition, SIOS LifeKeeper supports all major Linux distributions, including Red Hat Enterprise Linux, SUSE Linux Enterprise Server, CentOS, and Oracle Linux and accommodates a wide range of storage architectures. SIOS software has been adapted and optimized to run on these operating systems and the components are tested so ensure the SANless cluster solution will work on each OS.

Lastly, with the SIOS Protection Suite for Linux, you can run your business-critical applications in a flexible, scalable cloud environment, such as Amazon Web Services (AWS) without sacrificing performance, high availability, or disaster protection.

Linux Clustering in AWS

While cloud providers, such as AWS, provide high availability options, they do not provide the level of high availability and breadth of protection across the whole application infrastructure that customers demand and that you once achieved by using clusters before cloud computing. That is why AWS is partnering with SIOS. SIOS Protection Suite for Linux achieves these desired levels of high availability for our mutual customers and the critical applications they are moving to the AWS cloud.

SIOS Protection Suite for Linux on AWS provides all the elements you need to create a high availability Linux cluster in a virtual private cloud (VPC) within a single AWS Region across two Availability Zones. It also supports out-of-the-box protection for SAP systems, Oracle databases, and other business-critical applications.

SIOS and AWS offer SIOS Protection Suite Quickstart on AWS, which helps you create a fully configured and operational Linux high availability cluster in a few short steps. It sets up an AWS architecture for SIOS Protection Suite for Linux and deploys it into your AWS account in about half an hour. This Quick Start, available in the AWS Marketplace, is for enterprise users who want to deploy SIOS Protection Suite for Linux on AWS into their test or production environment.

SIOS Clustering for Linux

SIOS is a high availability company that has spent the past 20 years focused on delivering HA that is specifically designed for SAP, SQL, Linux, Oracle, and other applications. Its experience is built into its product, and installation and configuration take a fraction of the time and cost when compared to custom scripting with the Linux distributions. In addition, SIOS tests and validates new versions of operating systems and applications so its customers don’t have to. When a customer calls SIOS for support, they are connected to a high availability expert – someone who only focuses on HA and has been doing so for a very long time.

For more information, refer to the SIOS white paper, “Implementing High Availability in a Linux Environment.”

Additional References

https://whatis.techtarget.com/definition/clustered-storage

Reproduced from SIOS