Managing Serviceguard Sixteenth Edition, March 2009

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
Disk Mirroring
Serviceguard itself does not provide protection for data on your disks, but protection
is provided by HP’s Mirrordisk/UX product for LVM storage, and by the Veritas Volume
Manager for VxVM and CVM.
The logical volumes used for Serviceguard packages should be mirrored; so should
the cluster nodes’ root disks.
When you configure logical volumes using software mirroring, the members of each
mirrored set contain exactly the same data. If one disk fails, the storage manager
automatically keeps the data available by using the mirror. you can use three-way
mirroring in LVM (or additional plexes with VxVM) to allow for online backups or to
provide an additional level of high availability.
44 Understanding Serviceguard Hardware Configurations