Managing Serviceguard Nineteenth Edition, Reprinted June 2011

4 Planning and Documenting an HA Cluster
Building a Serviceguard cluster begins with a planning phase in which you gather information
about all the hardware and software components of the configuration.
This chapter assists you in the following planning areas:
• General Planning
• Hardware Planning (page 89)
• Power Supply Planning (page 93)
• Using a Quorum Server (page 95)
• LVM Planning (page 96)
• CVM and VxVM Planning (page 98)
• Cluster Configuration Planning (page 99)
• Package Configuration Planning (page 120)
Blank Planning Worksheets (page 355) contains a set of blank worksheets which you may find useful
as an offline record of important details of the configuration.
NOTE: Planning and installation overlap considerably, so you may not be able to complete the
worksheets before you proceed to the actual configuration. In that case, fill in the missing elements
to document the system as you proceed with the configuration.
Subsequent chapters describe configuration and maintenance tasks in detail.
General Planning
A clear understanding of your high availability objectives will help you to define your hardware
requirements and design your system. Use the following questions as a guide for general planning:
1. What applications must continue to be available in the event of a failure?
2. What system resources (processing power, networking, SPU, memory, disk space) are needed
to support these applications?
3. How will these resources be distributed among the nodes in the cluster during normal operation?
4. How will these resources be distributed among the nodes of the cluster in all possible
combinations of failures, especially node failures?
5. How will resources be distributed during routine maintenance of the cluster?
6. What are the networking requirements? Are all networks and subnets available?
7. Have you eliminated all single points of failure? For example:
• network points of failure.
• disk points of failure.
• electrical points of failure.
• application points of failure.
Serviceguard Memory Requirements
Serviceguard requires approximately 15.5 MB of lockable memory.
Planning for Expansion
When you first set up the cluster, you indicate a set of nodes and define a group of packages for
the initial configuration. At a later time, you may wish to add additional nodes and packages, or
you may wish to use additional disk hardware for shared data storage. If you intend to expand
88 Planning and Documenting an HA Cluster