Verifying port range availability on participating computers (Linux and UNIX)

This task describes the steps required to verify port range availability on participating computers. The port range is used by the Fast Communications Manager (FCM). FCM is a feature of Db2® that handles communications between database partition servers.

Before you begin

Verifying the port range availability on participating computers should be done after you install the instance-owning database partition server and before you install any participating database partition servers.

When you install the instance-owning database partition server on the primary computer, Db2 reserves a port range according to the specified number of logical database partition servers participating in partitioned database environment. The default range is four ports. For each server that participates in the partitioned database environment, you must manually configure the /etc/services file for the FCM ports. The range of the FCM ports depends on how many logical partitions you want to use on the participating computer. A minimum of two entries are required, DB2_instance and DB2_instance_END. Other requirements for the FCM ports specified on participating computers are:

The starting port number must match the starting port number of the primary computer
Subsequent ports must be sequentially numbered
Specified port numbers must be free

To make changes to the services file, you require root user authority.

Procedure

To verify the port range availability on participating computers:

Open the services file located in the /etc/services directory.
Locate the ports reserved for the Db2 Fast Communications Manager (FCM). The entries should appear similar to the following examples, depending on which version of Db2 is used.
For version 11.5.5 and older, Db2 reserves the first four available ports after 60000.
```
     DB2_db2inst1         60000/tcp
     DB2_db2inst1_1       60001/tcp
     DB2_db2inst1_2       60002/tcp
     DB2_db2inst1_END     60003/tcp
```
For version 11.5.6 and newer, Db2 reserves the first four available ports after 20000.
```
     DB2_db2inst1         20000/tcp
     DB2_db2inst1_1       20001/tcp
     DB2_db2inst1_2       20002/tcp
     DB2_db2inst1_END     20003/tcp
```
On each participating computer, open the services file and verify that the ports reserved for Db2 FCM in the services file of the primary computer are not being used.
In the event that the required ports are in use on a participating computer, identify an available port range for all computers and update each service file, including the services file on the primary computer.

What to do next

After you install the instance-owning database partition server on the primary computer, you must install your Db2 database product on the participating database partition servers. You can use the response file generated for the partitioning servers (default name is db2ese_addpart.rsp), you need to manually configure the /etc/services files for the FCM ports. The range of the FCM ports depend on how many logical partitions you want to use on the current machine. The minimum entries are for DB2_ and DB2__END two entries with consecutive free port numbers. The FCM port numbers used on each participating machines must have the same starting port number, and subsequent ports must be sequentially numbered.