Managing Serviceguard Eighteenth Edition, September 2010

cluster is running; see “Changing the Cluster Networking Configuration while the
Cluster Is Running” (page 367).
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.
Data Protection
It is required that you provide data protection for your highly available system, using
one of two methods:
• Disk Mirroring
• Disk Arrays using RAID Levels and Multiple Data Paths
44 Understanding Serviceguard Hardware Configurations