Managing dynamic location aliases

You can stop, cancel, modify, and start dynamic location aliases without stopping and restarting DDF or Db2.

Before you begin

Before you can modify existing dynamic location aliases, Db2 must be started.

About this task

Unlike statically defined location aliases, you cannot define or modify dynamic aliases by using the DSNJU003 utility, and the DSNJU004 utility does not print any information for dynamic location aliases.

When a static and dynamic location aliases are defined with the same name, Db2 accepts requests only to the dynamic location alias.

Procedure

To modify an existing dynamic location alias:

  1. Issue the MODIFY DDF command to stop or cancel the alias, where alias-name is the name of the alias.
    Option Description
    To stop the alias Issue the following command:
    -MODIFY DDF ALIAS(alias-name) STOP

    Db2 stops accepting new connection requests to the specified alias and existing database access threads continue to process connections to the specified alias. Inactive connections to the alias are automatically closed.
    To cancel the alias Issue the following command:
    -MODIFY DDF ALIAS(alias-name) CANCEL

    Db2 stops accepting new connection requests to the specified alias and existing database access threads that process connections to the specified alias are terminated. Inactive connections to the alias are automatically closed.
    Stopped and canceled dynamic location aliases do not start automatically when you start DDF. In a data sharing group, Db2 de-registers the alias with WLM, which means that Db2 is no longer included in sysplex workload balancing information, related to the alias, that is returned to remote client systems. Those steps are not needed in non-data sharing environments, because Db2 never registers the alias with WLM.
  2. Issue the MODIFY DDF command one or more times to modify the configuration of the alias. You can specify only one additional option with the MODIFY DDF command when you specify the ALIAS option. Therefore, you might need to issue the MODIFY DDF command more than once to make multiple changes to the configuration of the alias.
  3. Issue the MODIFY DDF command to start the alias.
    For example, you might issue the following command, where alias-name is the name of the alias:
    -MODIFY DDF ALIAS(alias-name) START

Example

For example, assume that a location alias named ALIAS1 was defined by the MODIFY DDF command, and it has the following configuration:
  • A port: 9000
  • An IPv4 address: 1.1.1.1

However, you want to modify the ALIAS1 location alias to use following configuration:

  • The default port
  • No IPv4 address
  • An IPv6 address: 3::3

You might issue the following sequence of example MODIFY DDF commands:

  1. The following command stops Db2 from accepting new connection requests to the ALIAS1 alias and cancels existing DBATs that are processing connections to it:
    -MODIFY DDF ALIAS(ALIAS1) CANCEL

    You can now modify the configuration of the alias.

  2. The following command removes the port value from the ALIAS1 alias:
    -MODIFY DDF ALIAS(ALIAS1) NPORT

    The group SQL port is now used instead.

  3. The following command removes the IPv4 address from the ALIAS1 alias. 
    -MODIFY DDF ALIAS(ALIAS1) NIPV4

    The member-specific IP address is returned in the server list instead.

  4. The following command adds an IPv6 address the ALIAS1 alias.
    -MODIFY DDF ALIAS(ALIAS1) IPV6(3::3)
  5. The following command starts the ALIAS1 alias:
    -MODIFY DDF ALIAS(ALIAS1) START

    DDF starts accepting new connections to the ALIAS1 alias and uses its new configuration.