Database Reference
In-Depth Information
Load Balancing and Failover
Single-component failure should not cause cluster-wide issues in RAC, but network interface failures can cause
heartbeat failures leading to node hangs, freeze, or reboots. So, prior to 11gR2, high availability was achieved by
implementing an OS-based feature such as IPMP (Sun), Link Aggregation (Sun), Bonding (Linux), etherChannel
(AIX), etc. It is outside the scope of this chapter to discuss individual host-based features, but essentially, these
features must provide failover and load balancing capabilities.
Linux Bonding is a prevalent feature in Linux clusters. Linux Bonding aggregates multiple network interface cards
(NICs) into a bonded logical interface. An IP address will be configured on that bonded interface, and Clusterware will
be configured to use that IP address for private network. Clusterware will configure a link local IP address on bonded
interface. Depending on the configured mode of the bonding driver, either load balancing or failover is configured,
or both are configured among the physical interfaces, as shown in Figure
9-6
.
Node 1
Node 2
Clusterware
Clusterware
bond0
bond0
switch
eth3
eth3
eth4
eth4
Figure 9-6.
Linux Bonding
If the OS feature is implemented for load balancing and failover, RAC does not handle load balancing or failover
for private network. RAC Database will use the IP address configured for private network, and it is up to the OS-based
high availability feature to monitor and manage the network interfaces.
HAIP
HAIP is a high availability feature introduced by Oracle Clusterware in database version 11.2. RAC database and
Clusterware are designed to implement high availability in private network with this feature. As HAIP is a feature
applicable only to private networks, HAIP supports IPv4 only; IPv6 is not supported.
9
Consider a configuration with two interfaces configured for private network. The HAIP feature will configure
one link local IP address in each interface. RAC database instances and ASM instances will send and receive buffers
through those two IP addresses, providing load balancing. Clusterware processes also monitor the network interfaces,
and if a failure is detected in an interface, then the link local IP address from the failed interface will be failed over to
9
Version 12c introduces a new feature, HAVIP, and you should not confuse HAVIP with the HAIP feature. The HAVIP feature is
applicable to public network, and the HAIP feature is applicable to private network.
