Installation guide

Section 2.4:Steps for Setting Up and Connecting the Cluster Hardware 43
It is not recommended to use a large UPS infrastructure as the sole source of power for the cluster. A
UPS solution dedicated to the cluster itself allows for more flexibility in terms of manageability and
availability.
A complete UPS system must be able to provide adequate voltage and current for a prolonged period
of time. While there is no single UPS to fit every power requirement, a solution can be tailored to fit
a particular configuration. Visit APC’s UPS configurator at http://www.apcc.com/template/size/apc
to find the correct UPS configuration for your server. The APC Smart-UPS product line ships with
software management for Red Hat Linux. The name of the RPM package is pbeagent.
If the cluster disk storage subsystem has two power supplies with separate power cords, set up two
UPS systems, and connect one power switch (or one cluster system’s power cord if not using power
switches) and one of the storage subsystem’s power cords to each UPS system. A redundant UPS
system configuration is shown in Figure 2–3, Redundant UPS System Configuration.
Figure 2–3 Redundant UPS System Configuration
An alternative redundant power configuration is to connect both power switches (or both cluster sys-
tems’ power cords) and the disk storage subsystem to the same UPS system. This is the most cost-ef-
fective configuration, and provides some protection against power failure. However, if a power outage
occurs, the single UPS system becomes a possible single point of failure. In addition, one UPS system
may not be able to provide enough power to all the attached devices for an adequate amount of time.
A single UPS system configuration is shown in Figure 2–4, Single UPS System Configuration.