How to configure a loopback connection with Db2 on AIX

Published On: 7. März 2024Last Updated: 7. März 2024Categories: Db2 LUW, Dev+OpsTags: loopback, node, SQL01224N0,7 min readViews: 180

By default, AIX does not allow 32-bit applications to attach to more than 11 shared memory segments per process, of which a maximum of 10 can be used for local Db2 connections.

The following steps outline how to configure DB2 to use a loopback connection:

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# Check your current DB2 communication protocols for your Db2 instance:
db2set DB2COMM

# Set your DB2 instance communication protocol to TCPIP, if not already set:
db2set DB2COMM=existing_protocol_names,TCPIP

# Determine which TCP/IP port number your instance is listening on for incoming requests:
db2 get dbm cfg | grep SVCENAME
# Example output:
# TCP/IP Service name (SVCENAME) = db2inst1

# Find the connection port used for your Db2 instance in your /etc/services file:
grep db2.*tcp /etc/services
# Example output:
# db2inst1 50000/tcp # Connection port for Dd2 instance

# Catalog the loopback node using the following command:
db2 catalog tcpip node new_nameremote hostname_or_ip server service_name
# Example:
# db2 catalog tcpip node LOOPNODE remote 127.0.0.1 server db2inst1

# Catalog the loopback database:
db2 catalog db MYDB as MYDBLOOP on /db2datapath

# Uncatalog the original database:
db2 uncatalog db MYDB

# Catalog the loopback database to the loopback node:
db2 catalog db database_name as loop_back_db_alias at node LOOPNODE
# Example:
# db2 catalog db MYDBLOOP as MYDB at node LOOPNODE

# Confirm that Db2 connection port is used:
db2 connect to MYDB
netstat -an | grep port_number
-- Example:
-- netstat -an | grep 50000

This technique can help to fix problems with SQLCODE -1224 on an SQL CONNECT.

An alternative is to specify AIX environment variable EXTSHM to increase the maximum number of shared memory segments to which a process can attach.

Links to IBM Db2 documentation

CATALOG TCPIP/TCPIP4/TCPIP6 NODE command https://www.ibm.com/docs/en/db2/11.5?topic=commands-catalog-tcpip-node
LIST NODE DIRECTORY command https://www.ibm.com/docs/en/db2/11.5?topic=commands-list-node-directory
CATALOG DATABASE command https://www.ibm.com/docs/en/db2/11.5?topic=commands-catalog-database
LIST DATABASE DIRECTORY command https://www.ibm.com/docs/en/db2/11.5?topic=commands-list-database-directory

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