Understanding and Designing Serviceguard Disaster Recovery Architectures

• CVM and CFS require link-level traffic communication (LLT) among the nodes, therefore Extended
Clusters cannot be configured in Cross-Subnet configurations with CVM or CFS. As a result,
only Extended Clusters using LVM volume groups are supported in Cross-Subnet configurations.
• Oracle RAC requires a common subnet for the RAC interconnect between nodes, therefore
Extended RAC Cross-Subnet Clusters are not supported.
• Each package subnet must be configured with a standby interface on the local bridged net.
The standby interface can be shared between subnets.
Configuration Requirements for all Extended Distance Clusters
The following configuration requirements are common for all Extended Distance Cluster and
Extended Cluster for RAC configurations:
• See Table 3 (page 49), Table 4 (page 49) and Table 5 (page 51) for information about the
Products, Product revisions and Volume Managers supported in Extended Clusters.
• The network interfaces used for cluster nodes must support DLPI
1
. The network switches used
in the configuration must also support DLPI. DLPI support is not required for Quorum Server
nodes.
• There can be separate TCP/IP networking links and Fibre Channel data links between the
data centers, or both TCP/IP networking and Fibre Channel data can go over common WDM
2
(Wave Division Multiplexing), SONET or SDH links between the data centers. See the section
below “TCP/IP Network and Fibre Channel Data links between the data centers” for more
detail.
• A minimum of two heartbeat paths must be configured for all cluster nodes. The preferred
solution is two separate heartbeat subnets configured in the cluster, each going over a
separately routed
3
network path to the other data centers. Or, there can be a single dedicated
heartbeat subnet with Primary and Standby LANs configured for it, each going over a
separately routed3 network path to the other data centers. For clusters using CVM 3.5, only
a single heartbeat subnet is supported, so you must have both Primary and Standby LANs
configured for the heartbeat subnet on all nodes. Multiple heartbeat subnets are supported
with LVM, SLVM, VxVM, CVM 4.1, CFS 4.1, CVM 5.0, CFS 5.0, CVM 5.0.1, and CFS 5.0.1.
For EC RAC clusters, HP recommends that you to have an additional network for Oracle RAC
cache fusion traffic. It is acceptable to use a single Standby network to provide backup for
both the heartbeat network and the RAC cache fusion network however, it can only provide
failover capability for one of these networks at a time. The RAC CRS heartbeat must go over
the same network interfaces as the Serviceguard heartbeat, however CRS only supports one
heartbeat (primary: standby pair).
• In Serviceguard the Heartbeat subnets must be common to all data centers, with the exception
of Cross-Subnet configurations
• Cross-Subnet configurations are supported with Extended Cluster configurations with up to 16
nodes. This allows the nodes in each data center to configure their heartbeats on subnets that
are locally unique to their own data centers. The heartbeats must be statically routed; static
route entries must be configured on each node to route the heartbeats through different paths.
Network routing must be configured between minimum two pairs of subnets between the data
centers, and the routing between each subnet pair must be configured such that the failure of
a single router or LAN segment will not take out all heartbeats between the data centers. There
must be a minimum of two heartbeat subnets in each data center and each heartbeat subnet
must have a Standby subnet. The heartbeat between the data centers requires TCP/IP
connectivity (for example, DLPI connectivity is not required between the data centers, but is
required within the data centers). SGeRAC, CVM, and CFS are not supported in Cross-Subnet
cluster configurations. All other requirements listed in this section still apply for Cross-Subnet
configurations, unless otherwise noted.
54 Extended Distance Cluster Configurations