DB2 Version 9.7 for Linux, UNIX, and Windows

Creating node configuration files

If your database is to operate in a partitioned database environment, you must create a node configuration file called db2nodes.cfg.

About this task

To enable database partitioning, the db2nodes.cfg file must be located in the sqllib subdirectory of the home directory for the instance before you start the database manager. This file contains configuration information for all database partitions in an instance, and is shared by all database partitions for that instance.

Windows considerations

If you are using DB2® Enterprise Server Edition on Windows, the node configuration file is created for you when you create the instance. You should not attempt to create or modify the node configuration file manually. You can use the db2ncrt command to add a database partition server to an instance. You can use the db2ndrop command to drop a database partition server from an instance. You can use the db2nchg command to modify a database partition server configuration including moving the database partition server from one computer to another; changing the TCP/IP host name; or, selecting a different logical port or network name.

Note: You should not create files or directories under the sqllib subdirectory other than those created by the database manager to prevent the loss of data if an instance is deleted. There are two exceptions. If your system supports stored procedures, put the stored procedure applications in the function subdirectory under the sqllib subdirectory. The other exception is when user-defined functions (UDFs) have been created. UDF executables are allowed in the same directory.

The file contains one line for each database partition that belongs to an instance. Each line has the following format:

dbpartitionnum hostname [logical-port [netname]]

Tokens are delimited by blanks. The variables are:

dbpartitionnum

The database partition number, which can be from 0 to 999, uniquely defines a database partition. Database partition numbers must be in ascending sequence. You can have gaps in the sequence.

Once a database partition number is assigned, it cannot be changed. (Otherwise the information in the distribution map, which specifies how data is distributed, would be compromised.)

If you drop a database partition, its database partition number can be used again for any new database partition that you add.

The database partition number is used to generate a database partition name in the database directory. It has the format:

NODE nnnn

The nnnn is the database partition number, which is left-padded with zeros. This database partition number is also used by the CREATE DATABASE and DROP DATABASE commands.

hostname: The hostname of the IP address for inter-partition communications. Use the fully-qualified name for the hostname. The /etc/hosts file also should use the fully-qualified name. If the fully-qualified name is not used in the db2nodes.cfg file and in the /etc/hosts file, you might receive error message SQL30082N RC=3.
(There is an exception when netname is specified. In this situation, netname is used for most communications, with hostname only being used for db2start, db2stop, and db2_all.)

logical-port

This parameter is optional, and specifies the logical port number for the database partition. This number is used with the database manager instance name to identify a TCP/IP service name entry in the etc/services file.

The combination of the IP address and the logical port is used as a well-known address, and must be unique among all applications to support communications connections between database partitions.

For each hostname, one logical-port must be either 0 (zero) or blank (which defaults to 0). The database partition associated with this logical-port is the default node on the host to which clients connect. You can override this with the DB2NODE environment variable in db2profile script, or with the sqlesetc() API.

netname: This parameter is optional, and is used to support a host that has more than one active TCP/IP interface, each with its own hostname.

The following example shows a possible node configuration file for a system on which SP2EN1 has multiple TCP/IP interfaces, two logical partitions, and uses SP2SW1 as the DB2 database interface. It also shows the database partition numbers starting at 1 (rather than at 0), and a gap in the dbpartitionnum sequence:

Table 1. Database partition number example table.
`dbpartitionnum`	`hostname`	`logical-port`	`netname`
1	SP2EN1.mach1.xxx.com	0	SP2SW1
2	SP2EN1.mach1.xxx.com	1	SP2SW1
4	SP2EN2.mach1.xxx.com	0
5	SP2EN3.mach1.xxx.com

You can update the db2nodes.cfg file using an editor of your choice. (The exception is: an editor should not be used on Windows.) You must be careful, however, to protect the integrity of the information in the file, as database partitioning requires that the node configuration file is locked when you issue START DBM and unlocked after STOP DBM ends the database manager. The START DBM command can update the file, if necessary, when the file is locked. For example, you can issue START DBM with the RESTART option or the ADD DBPARTITIONNUM option.

Note: If the STOP DBM command is not successful and does not unlock the node configuration file, issue STOP DBM FORCE to unlock it.