Format of the Db2 node configuration file

The format of the db2nodes.cfg file on Linux® and UNIX operating systems is as follows:

dbpartitionnum hostname logicalport netname resourcesetname

dbpartitionnum, hostname, logicalport, netname, and resourcesetname are defined in the following section.

The format of the db2nodes.cfg file on Windows operating systems is as follows:

dbpartitionnum hostname computername logicalport netname resourcesetname

On Windows operating systems, these entries to the db2nodes.cfg are added by the db2ncrt or START DBM ADD DBPARTITIONNUM commands. The entries can also be modified by the db2nchg command. You should not add these lines directly or edit this file.

dbpartitionnum

A unique number, between 0 and 999, that identifies a database partition server in a partitioned database system.

To scale your partitioned database system, you add an entry for each database partition server to the db2nodes.cfg file. The dbpartitionnum value that you select for additional database partition servers must be in ascending order, however, gaps can exist in this sequence. You can choose to put a gap between the dbpartitionnum values if you plan to add logical partition servers and want to keep the nodes logically grouped in this file.

This entry is required.

hostname

The TCP/IP host name of the database partition server for use by the FCM. This entry is required. Canonical hostname is strongly recommended.

When the system has more than one network interface card installed and the hostname that is used in the db2nodes.cfg file cannot be resolved to be the default host of the system, it might be treated as a remote host. This setup imposes a limitation that database migration cannot be done successfully because the local database directory cannot be found if the instance is not started. Therefore, HADR might require the hostname to match the name that is used by the operating system to identify the host to make migration possible. In addition to this, the operating system name of the host must be specified in db2nodes.cfg when it is running in a Tivoli® SA MP, PowerHA® SystemMirror®, and other high availability environments, including the Db2 fault monitor.

Starting with Db2 Version 9.1, both TCP/IPv4 and TCP/IPv6 protocols are supported. The method to resolve host names has changed.

While the method used in pre-Version 9.1 releases resolves the string as defined in the db2nodes.cfg file, the method in Version 9.1 or later tries to resolve the Fully Qualified Domain Names (FQDN) when short names are defined in the db2nodes.cfg file. Specifying short configured for fully qualified host names, this may lead to unnecessary delays in processes that resolve host names.

To avoid any delays in Db2 commands that require host name resolution, use any of the following workarounds:

1. If short names are specified in the db2nodes.cfg files and the operating system host name file, specify the short name and the fully qualified domain name for host name in the operating system host files.
2. To use only IPv4 addresses when you know that the Db2 server listens on an IPv4 port, issue the following command:

   db2 catalog tcpip4 
       node db2tcp2 remote 192.0.32.67 
       server db2inst1 with "Look up IPv4 address from 192.0.32.67"

3. To use only IPv6 addresses when you know that the Db2 server listens on an IPv6 port, issue the following command:

   db2 catalog tcpip6 
       node db2tcp3 1080:0:0:0:8:800:200C:417A 
       server 50000 
       with "Look up IPv6 address from 1080:0:0:0:8:800:200C:417A"

logicalport

Specifies the logical port number for the database partition server. This field is used to specify a particular database partition server on a workstation that is running logical database partition servers.

Db2 reserves a port range (for example, 60000 - 60003) in the /etc/services file for interpartition communications at the time of installation. This logicalport field in db2nodes.cfg specifies which port in that range you want to assign to a particular logical partition server.

If there is no entry for this field, the default is 0. However, if you add an entry for the netname field, you must enter a number for the logicalport field.

If you are using logical database partitions, the logicalport value you specify must start at 0 and continue in ascending order (for example, 0,1,2).

Furthermore, if you specify a logicalport entry for one database partition server, you must specify a logicalport for each database partition server listed in your db2nodes.cfg file.

Each physical server must have a logical node 0.

This field is optional only if you are not using logical database partitions or a high speed interconnect.

netname

Specifies the host name or the IP address of the high speed interconnect for FCM communication.

If an entry is specified for this field, all communication between database partition servers (except for communications as a result of the db2start, db2stop, and db2_all commands) is handled through the high speed interconnect.

This parameter is required only if you are using a high speed interconnect for database partition communications.

resourcesetname

The resourcesetname defines the operating system resource that the node should be started in. The resourcesetname is for process affinity support, used for Multiple Logical Nodes (MLNs). This support is provided with a string type field formerly known as quadname.

This parameter is only supported on AIX®.

On AIX, this concept is known as "resource sets", refer to AIX documentation for more information about resource management.

On Windows operating systems, process affinity for a logical node can be defined through the DB2PROCESSORS registry variable.

On Linux operating systems, the resourcesetname column defines a number that corresponds to a Non-Uniform Memory Access (NUMA) node on the system. The system utility numactl must be available as well as a 2.6 Kernel with NUMA policy support.

The netname parameter must be specified if the resourcesetname parameter is used.