Part I Installation and setup #

SUSE® Linux Enterprise High Availability is an integrated suite of open source clustering technologies. It enables you to implement highly available physical and virtual Linux clusters, and to eliminate single points of failure. It ensures the high availability and manageability of critical network resources including data, applications, and services. Thus, it helps you maintain business continuity, protect data integrity, and reduce unplanned downtime for your mission-critical Linux workloads.

It ships with essential monitoring, messaging, and cluster resource management functionality (supporting failover, failback, and migration (load balancing) of individually managed cluster resources).

This chapter introduces the main product features and benefits of SUSE Linux Enterprise High Availability. Inside you will find several example clusters and learn about the components making up a cluster. The last section provides an overview of the architecture, describing the individual architecture layers and processes within the cluster.

This chapter shows an overview of the steps to set up a working and supported High Availability cluster. Alternatively, to set up a basic two-node cluster with only the default options, see Démarrage rapide de l'installation et de la configuration.

The following section informs you about system requirements and prerequisites for SUSE® Linux Enterprise High Availability. It also includes recommendations for cluster setup.

The CRM Shell (crmsh) uses passwordless SSH access for communication between the nodes. If you set up the cluster with crm cluster init, the script checks for SSH keys and generates them if they do not exist. If you set up the cluster with the YaST cluster module, you must configure the SSH keys yourself.

By default, crmsh performs certain operations as the root user. However, if you cannot allow passwordless root SSH access, you can set up the cluster as a user with sudo privileges instead.

The packages for configuring and managing a cluster are included in the High Availability installation pattern. This pattern is only available after the SUSE Linux Enterprise High Availability extension (SLE HA) is installed. SLE HA can be installed along with SUSE Linux Enterprise Server (SLES), or after SLES is already installed.

SUSE Linux Enterprise High Availability includes bootstrap scripts to simplify the installation of a cluster. You can use these scripts to set up the cluster on the first node, add more nodes to the cluster, remove nodes from the cluster, and adjust certain settings in an existing cluster.

The YaST cluster module allows you to set up a cluster manually or to modify options for an existing cluster.

After you have installed and set up an initial cluster, you can extend the cluster by cloning existing nodes with AutoYaST and adding the clones to the cluster.

AutoYaST uses profiles that contain installation and configuration data. A profile tells AutoYaST what to install and how to configure the installed system to get a ready-to-use system in the end. This profile can then be used for mass deployment in different ways (for example, to clone existing cluster nodes).

For detailed instructions on how to use AutoYaST in various scenarios, see the AutoYaST Guide for SUSE Linux Enterprise Server 15 SP7.