Managing HP Serviceguard for Linux, Tenth Edition, September 2012

cluster node. To prevent this and other problems, Serviceguard imposes the following
restrictions:
• A maximum of 30 network interfaces per node is supported. The interfaces can be
physical NIC ports, VLAN interfaces, Channel Bonds, or any combination of these.
• Only port-based and IP-subnet-based VLANs are supported. Protocol-based VLAN
is not supported because Serviceguard does not support any transport protocols
other than TCP/IP.
• Each VLAN interface must be assigned an IP address in a unique subnet.
• Using VLAN in a Wide Area Network cluster is not supported.
Additional Heartbeat Requirements
VLAN technology allows great flexibility in network configuration. To maintain
Serviceguard’s reliability and availability in such an environment, the heartbeat rules
are tightened as follows when the cluster is using VLANs:
1. VLAN heartbeat networks must be configured on separate physical NICs or Channel
Bonds, to avoid single points of failure.
2. Heartbeats are still recommended on all cluster networks, including VLANs.
3. If you are using VLANs, but decide not to use VLANs for heartbeat networks,
heartbeats are recommended for all other physical networks or Channel Bonds
specified in the cluster configuration file.
Volume Managers for Data Storage
A volume manager lets you create units of disk storage that are more flexible than
individual disk partitions. These units can be used on single systems or in high-availability
clusters. HP Serviceguard for Linux uses the Linux Logical Volume Manager (LVM) which
creates redundant storage groups. This section provides an overview of volume
management with LVM. See “Creating the Logical Volume Infrastructure ” (page 169) in
Chapter 5 for information about configuring volume groups, logical volumes, and file
systems for use in Serviceguard packages.
In HP Serviceguard for Linux, the supported shared data storage type is disk arrays which
configure redundant storage in hardware.
In a disk array, the basic element of storage is a LUN, which already provides storage
redundancy via RAID1 or RAID5. Before you can use the LUNs, you must partition them
using fdisk.
In LVM, you manipulate storage in one or more volume groups. A volume group is built
by grouping individual physical volumes. Physical volumes can be disk partitions or LUNs
that have been marked as physical volumes as described below.
You use the pvcreate command to mark the LUN as physical volumes. Then you use
the vgcreate command to create volume groups out of one or more physical volumes.
Once configured, a volume group can be subdivided into logical volumes of different
Volume Managers for Data Storage 81