Managing HP Serviceguard for Linux Ninth Edition, April 2009

• You must group high availability applications, services, and data, whose control
needs to be transferred together, on a single volume group or a series of volume
groups.
• You must not group two different high availability applications, services, or data,
whose control needs to be transferred independently, on the same volume group.
• Your root disk must not belong to a volume group that can be activated on another
node.
Volume Groups and Physical Volume Worksheet
You can organize and record your physical disk configuration by identifying which
physical disks, LUNs, or disk array groups will be used in building each volume group
for use with high availability applications. Use the Volume Group and Physical Volume
worksheet (page 313).
NOTE: HP recommends that you use volume group names other than the default
volume group names (vg01, vg02, etc.). Choosing volume group names that represent
the high availability applications they are associated with (e.g., /dev/vgdatabase)
will simplify cluster administration.
Cluster Configuration Planning
A cluster should be designed to provide the quickest possible recovery from failures.
The actual time required to recover from a failure depends on several factors:
• The length of the MEMBER_TIMEOUT; see the description of this parameter under
“Cluster Configuration Parameters ” for recommendations.
• The design of the run and halt instructions in the package control script. They
should be written for fast execution.
• The application and database recovery time. They should be designed for the
shortest recovery time.
In addition, you must provide consistency across the cluster so that:
• User names are the same on all nodes.
• UIDs are the same on all nodes.
• GIDs are the same on all nodes.
• Applications in the system area are the same on all nodes.
• System time is consistent across the cluster.
• Files that could be used by more than one node, such as /usr or/opt files, must
be the same on all nodes.
Cluster Configuration Parameters
You need to define a set of cluster parameters. These are stored in the binary cluster
configuration file, which is distributed to each node in the cluster. You configure these
100 Planning and Documenting an HA Cluster