Managing Serviceguard Nineteenth Edition, Reprinted June 2011

IMPORTANT: Although cross-subnet topology can be implemented on a single site, it is most
commonly used by extended-distance clusters, and specifically site-aware disaster-tolerant clusters,
which require Metrocluster (HP add-on software).
Design and configuration of such clusters are covered in the disaster-tolerant documentation
delivered with Serviceguard. For more information, see the following documents under http://
www.hp.com/go/hpux-serviceguard-docs:
• Understanding and Designing Serviceguard Disaster Tolerant Architectures
• Designing Disaster Tolerant HA Clusters Using Metrocluster and Continentalclusters
• The white paper Configuration and Administration of Oracle 10g R2 RAC Database in HP
Metrocluster
Replacing Failed Network Cards
Depending on the system configuration, it is possible to replace failed network cards while the
cluster is running. The process is described under “Replacement of LAN Cards” in the chapter
“Troubleshooting Your Cluster.” With some restrictions, you can also add and delete LAN interfaces
to and from the cluster configuration while the cluster is running; see “Changing the Cluster
Networking Configuration while the Cluster Is Running” (page 284).
Redundant Disk Storage
Each node in a cluster has its own root disk, but each node is also physically connected to several
other disks in such a way that more than one node can obtain access to the data and programs
associated with a package it is configured for. This access is provided by a Storage Manager,
such as Logical Volume Manager (LVM), or Veritas Volume Manager (VxVM) (or Veritas Cluster
Volume Manager (CVM). LVM and VxVM disk storage groups can be activated by no more than
one node at a time, but when a failover package is moved, the storage group can be activated
by the adoptive node. All of the disks in the storage group owned by a failover package must be
connected to the original node and to all possible adoptive nodes for that package. Disk storage
is made redundant by using RAID or software mirroring.
Supported Disk Interfaces
The following interfaces are supported by Serviceguard for disks that are connected to two or more
nodes (shared data disks):
• Single-ended SCSI
• SCSI
• Fibre Channel
Not all SCSI disks are supported. See the HP Unix Servers Configuration Guide (available through
your HP representative) for a list of currently supported disks.
NOTE: In a cluster that contains systems with PCI SCSI adapters, you cannot attach both PCI and
NIO SCSI adapters to the same shared SCSI bus.
External shared Fast/Wide SCSI buses must be equipped with in-line terminators for disks on a
shared bus. Refer to the “Troubleshooting” chapter for additional information.
When planning and assigning SCSI bus priority, remember that one node can dominate a bus
shared by multiple nodes, depending on what SCSI addresses are assigned to the controller for
each node on the shared bus. All SCSI addresses, including the addresses of all interface cards,
must be unique for all devices on a shared bus.
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