Using Serviceguard Extension for RAC, 8th Edition, March 2009

Shared Storage
It is expected the shared storage is available when the RAC instance is started. Since the RAC
instance expects the shared storage to be available, ensure the shared storage is activated. For
SLVM, the shared volume groups must be activated and for CVM, the disk group must be
activated. For CFS, the cluster file system must be mounted.
Oracle Cluster Software requires shared storage for the Oracle Cluster Registry (OCR) and a vote
device. Automatic Storage Management (ASM) can not be used for the OCR and vote device
since these files must be accessible before Oracle Cluster Software starts.
For Oracle 10g, the minimum required size for each copy of the OCR is 100MB and for each vote
disk is 20 MB. For Oracle 11gR1, the minimum required size for each copy of the OCR is 256MB
and for each vote disk is 256 MB.
The Oracle OCR and vote device can be created on supported shared storage, including SLVM
logical volumes, CVM raw volumes, and CFS file systems.
Network Planning for Cluster Communication
The network for cluster communication is used for private internal cluster communications.
Although one network adapter per node is sufficient for the private network, it is recommended
that a minimum of two network adapters for each network to be used for higher availability.
The following are the major categories of inter-cluster traffic in an SGeRAC environment:
• Serviceguard HeartBeat (SG-HB): Serviceguard heartbeat and communications traffic.
Supported over single or multiple subnet networks.
• Cluster Synchronization Services Heartbeat (CSS-HB): CSS heartbeat traffic and
communications traffic for Oracle Clusterware. CSS-HB uses a single logical connection over
a single subnet network.
• RAC Interconnect (RAC-IC): RAC instance peer to peer traffic and communications for
Global Cache Service (GCS) and Global Enqueue Service (GES), formally Cache Fusion (CF)
and Distributed Lock Manager (DLM). Network HA is provided by the HP-UX platform
(Serviceguard or Auto Port Aggregation (APA)).
• Automatic Storage Management Interconnect (ASM-IC) (only when using ASM, Automatic
Storage Management): ASM instance peer to peer traffic. When it exists, ASM-IC should be
on the same network as CSS-HB. Network HA is required either through Serviceguard
failover or APA bonding.
• Global Atomic Broadcast/Link Level Traffic (GAB/LLT) (only when using CFS/CVM):
Symantec cluster heartbeat and communications traffic. GAB/LLT communicates over link
level protocol (DLPI) and supported over Serviceguard heartbeat subnet networks, including
primary and standby links.
The most common network configurations is to have all interconnect traffic for cluster
communications to go on a single heartbeat network that is redundant so that Serviceguard
monitors the network and resolves interconnect failures by cluster reconfiguration.
The following are situations when it is not possible to place all interconnect traffic on a single
network:
• RAC GCS (cache fusion) traffic may be very high, so an additional dedicated heartbeat
network for Serviceguard needs to be configured.
• Some networks, such as Infiniband, are not supported by CFS/CVM, so the CSS-HB/RAC-IC
traffic may need to be on a separate network that is different from SG-HB network.
• Certain configurations for fast re-configurations requires a dual Serviceguard heartbeat
network, and CSS-HB/RAC-IC does not support multiple networks for HA purposes.
• In a multiple database configuration, RAC-IC traffic of one database may interfere with
RAC-IC traffic of another database, so the RAC-IC traffic of databases may need to be
separated.
Network Planning for Cluster Communication 31