1. Real Application Clusters Administration and Deployment Guide
  2. Administering Multiple Cluster Interconnects on Linux and UNIX Platforms

Administering Multiple Cluster Interconnects on Linux and UNIX Platforms

In Oracle RAC environments that run on Linux and UNIX platforms, you can use the CLUSTER_INTERCONNECTS initialization parameter to specify an alternative interconnect to the one Oracle Clusterware is using for the private network.

Note:

The CLUSTER_INTERCONNECTS initialization parameter should not be set to highly available IP (HAIP) addresses provided by Redundant Interconnect Usage. HAIP addresses are recognized automatically.

If you set multiple values for CLUSTER_INTERCONNECTS, then Oracle AI Database uses all of the network interfaces that you specify for the interconnect, providing load balancing if all of the listed interconnects remain operational. You must use identical values, including the order in which the interconnects are listed, on all instances of your database when defining multiple interconnects with this parameter.

Note:

Oracle does not recommend setting the CLUSTER_INTERCONNECTS initialization parameter, which overrides the default interconnect settings at the operating system level.

Instead, the best practice is to use Redundant Interconnect Usage, available with Oracle Grid Infrastructure for Oracle RAC and Oracle Real Application Clusters One Node databases, and later. Oracle AI Database uses operating system-based network bonding technologies to enable high availability (and load balancing) for network interface cards meant to be used as the cluster interconnect. If you want to use multiple database versions in one cluster, you can combine both techniques. Redundant Interconnect Usage will use the interfaces as presented on the operating system level, regardless of bonding. For more information regarding bonding technologies contact your operating system vendor.

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Use Cases for Setting the CLUSTER_INTERCONNECTS Parameter

The CLUSTER_INTERCONNECTS initialization parameter requires an IP address. It enables you to specify multiple IP addresses, separated by colons. Oracle RAC network traffic is distributed between the specified IP addresses.

Note:

Oracle recommends that all databases and Oracle Clusterware use the same interconnect network.

Typically, you set the CLUSTER_INTERCONNECTS parameter only in the following situations:

  • The cluster is running multiple databases and you need the interconnect traffic to be separated and you do not use Redundant Interconnect Usage.
  • You have a single IP address that is made highly available by the operating system, and it does not have a stable interface name (for example, the name can change when you restart).

Do not set the CLUSTER_INTERCONNECTS parameter for the following common configurations:

  • If you want to use Redundant Interconnect Usage.
  • If you have only one cluster interconnect.
  • If the default cluster interconnect meets the bandwidth requirements of your Oracle RAC database, which is typically the case.

Consider the following important points when specifying the CLUSTER_INTERCONNECTS initialization parameter:

  • The CLUSTER_INTERCONNECTS initialization parameter is useful only in Linux and UNIX environments where UDP IPC is enabled.
  • Specify a different value for each instance of the Oracle RAC database when setting the CLUSTER_INTERCONNECTS initialization parameter in the parameter file.
  • The IP addresses you specify for the different instances of the same database on different nodes must belong to network adapters that connect to the same interconnect network.
  • If you specify multiple IP addresses for this parameter, then list them in the same order for all instances of the same database. For example, if the parameter for the first instance on node1 lists the IP addresses of the alt0:, fta0:, and ics0: devices in that order, then the parameter for the second instance on node2 must list the IP addresses of the equivalent network adapters in the same order.
  • If an operating system error occurs while Oracle AI Database is writing to the interconnect that you specify with the CLUSTER_INTERCONNECTS parameter, then Oracle AI Database returns an error even if some other interfaces are available. This is because the communication protocols between Oracle AI Database and the interconnect can vary greatly depending on your platform. See your Oracle AI Database platform-specific documentation for more information.

Example

Consider setting CLUSTER_INTERCONNECTS when a single cluster interconnect cannot meet your bandwidth requirements. You may need to set this parameter in data warehouse environments with high interconnect bandwidth demands from one or more databases that cannot use Redundant Interconnect Usage.

For example, if you have two databases with high interconnect bandwidth requirements, then you can override the default interconnect provided by your operating system and nominate a different interconnect for each database using the following syntax in each server parameter file where ipn is an IP address in standard dot-decimal format, for example: 144.25.16.214:

Database One: crm1.CLUSTER_INTERCONNECTS = ip1
Database Two: ext1.CLUSTER_INTERCONNECTS = ip2

If you have one database with high bandwidth demands, then you can nominate multiple interconnects using the following syntax:

CLUSTER_INTERCONNECTS = ip1:ip2:...:ipn

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