DB2 Version 9.7 for Linux, UNIX, and Windows
After you install a DB2 Server product > Post-installation tasks > Partitioned database environment >

Enabling communications between database partition servers (Linux® and UNIX®)

This task describes how to enable communication between the database partition servers that participate in your partitioned database system. Communication between database partition servers is handled by the Fast Communications Manager (FCM). To enable FCM, a port or port range must be reserved in the /etc/services file on each computer in your partitioned database system.

You must have a user ID with root authority.

You must perform this task on all computers that participate in the instance.

The number of ports to reserve for FCM is equal to the maximum number of database partitions hosted, or potentially hosted, by any computer in the instance.

In the following example, the db2nodes.cfg file contains these entries:

0 server1 0  
1 server1 1  
2 server2 0  
3 server2 1  
4 server2 2  
5 server3 0  
6 server3 1  
7 server3 2  
8 server3 3  

Assume that the FCM ports are numbered starting at 60000. In this situation:

All computers must reserve 60000, 60001, 60002, and 60003, since this is the largest port range required by any computer in the instance.

If you use a high availability solution such as High Availability Cluster Multi-Processing (HACMP™) or Tivoli® System Automation to fail over database partitions from one computer to another, you must account for potential port requirements. For example, if a computer normally hosts four database partitions, but another computer's two database partitions could potentially fail over to it, six ports must be planned for that computer.

When you create an instance, a port range is reserved on the primary computer. The primary computer is also known as the instance-owning computer. However, if the port range originally added to the /etc/services file is not sufficient for your needs, you will need to extend the range of reserved ports by manually adding additional entries.

To enable communications between servers in a partitioned database environment using /etc/services:

  1. Log on to the primary computer (instance owning computer) as a user with root authority.
  2. Create an instance.
  3. View the default port range that has been reserved in the /etc/services file. In addition to the base configuration, the FCM ports should appear similar to the following:
       db2c_db2inst1         50000/tcp
       #Add FCM port information 
       DB2_db2inst1          60000/tcp
       DB2_db2inst1_1        60001/tcp
       DB2_db2inst1_2        60002/tcp
       DB2_db2inst1_END      60003/tcp
    By default, the first port (50000) is reserved for connection requests, and the first available four ports above 60000 are reserved for FCM communication. One port is for the instance-owning database partition server and three ports are for logical database partition servers that you might choose to add to the computer after installation is complete.

    The port range must include a start and an END entry. Intermediate entries are optional. Explicitly including intermediate values can be useful for preventing other applications from using these ports, but these entries are not verified by the database manager.

    DB2® port entries use the following format:

       DB2_instance_name_suffix  port_number/tcp  # comment

    where:

  4. Ensure that there are sufficient ports reserved for FCM communication. If the range of reserved ports is insufficient, add new entries to the file.
  5. Log on as a root user to each computer participating in the instance and add identical entries to the /etc/services file.
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