Heartbeat Cluster Components; Architecture - Novell SUSE LINUX ENTERPRISE SERVER 10 SP2 HEARTBEAT Manual

1.4 Heartbeat Cluster Components

The following components make up a Heartbeat version 2 cluster:
• From 2 to 16 Linux servers, each containing at least one local disk device.
• Heartbeat software running on each Linux server in the cluster.
• Optional: A shared disk subsystem connected to all servers in the cluster.
• Optional: High-speed Fibre Channel cards, cables, and switch used to connect the
servers to the shared disk subsystem.
• At least two communications mediums over which Heartbeat servers can commu-
nicate. These currently include Ethernet (mcast, ucast, or bcast) or Serial.
• A STONITH device. A STONITH device is a power switch which the cluster uses
to reset nodes that are considered dead. Resetting non-heartbeating nodes is the
only reliable way to ensure that no data corruption is performed by nodes that hang
and only appear to be dead.
See The High-Availability Linux Project
STONITH] for more information on STONITH.

1.5 Architecture

This section provides a brief overview of the Heartbeat architecture. It identifies and
provides information on the Heartbeat architectural components, and describes how
those components interoperate.
1.5.1 Architecture Layers
Heartbeat has a layered architecture.
illustrates the different layers and their associated components.
8 Heartbeat
[http://www.linux-ha.org/
Figure 1.6, "Heartbeat Architecture" (page 9)