Managing Serviceguard 13th Edition, February 2007

Understanding Serviceguard Hardware Configurations
Redundant Disk Storage
Chapter 2 43
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) on
HP-UX releases that support it; see “About VERITAS CFS and CVM” on
page 27). 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.