Sample Configurations with SGeRAC and Oracle RAC 10gR2, March 2009

Local LAN failover using APA

When APA is used where the network interface cards are bonded, APA provides traffic distribution

and load balancing capability among multiple physical network interface cards (NIC) or links. Load

balance may be a benefit which is desirable to configurations where a single interface is insufficient

to handle the network traffic. When a physical NIC or link fails, APA provides HA by distributing

traffic among remaining NIC or links. One virtual link is presented to OC and APA network load

balancing is transparent to OC. APA requires the same type of NIC. Since APA network connections

go to the same switch, a switch failure means outage of the client network.

When APA/Hot Standby is used, APA/Hot Standby provides the primary-to-hot-standby failover by

rerouting traffic from failed primary link to hot standby link. APA/Hot Standby does not load

balance. Serviceguard does not monitor this network. One virtual network link is presented to OC

and the physical failover is transparent to OC because the same virtual network link remains

available. Both NICs must be the same type as in APA.

Remote failover

OC fails over the VIP address to a surviving node on a catastrophic failure such as node failure,

instance failure, storage failure, or network failure.

Network for cluster communication

Serviceguard, OC, and each RAC instance maintain communication with peers on other nodes.

When communication is broken, either through network partition or node failure, each of these

components needs to reform its membership and eject non-members as needed.

In CFS and CVM (4.1/5.0) configurations, Symantec Veritas’ Group Membership Service/Atomic

Broadcast and Low Latency Transport (GAB/LLT) also uses the cluster interconnect for peer to peer

communications.

The categories of traffic between nodes are distinguished as follows:

• SG-HB – Serviceguard heartbeat and communications traffic. Supported over single or

multiple subnet networks.

• CSS-HB – Cluster Synchronization Service (CSS) heartbeat traffic and communications traffic

for Oracle Clusterware. CSS-HB uses a single logical connection over a single subnet

network.

• RAC-DB-IC – RAC instance peer to peer traffic and communications for Global Cache Service

(GCS) and Global Enqueue Service (GES), formerly Cache Fusion (CF) and Distributed Lock

Manager (DLM). Network HA is provided by the HP-UX 11i platform (Serviceguard or APA

bonding).

• ASM-IC – Applicable only when using Automatic Storage Management (ASM). 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.

• GAB/LLT – Applicable 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. GAB/LLT

is not supported over APA or virtual LANs (VLAN).

Note that each category maintains its own timeout for which nodes may be evicted from its respective

membership.

The interconnect network requires HA configurations. When a single network failure occurs, for

example LAN card or switch failures, all the cluster nodes continue to operate. Without HA, a single

network failure results in a network partition between the nodes and evicts nodes are halted.