Creating multiple DB2 database instances on Linux

Attention

For each instance that you want to create, log in as the instance owner before creating the instance.
Use the DB2® Command Line Processor to enter commands.
After creating the instance, add the instance to the user environment variable. The instance is then visible in the DB2 Control Center.
An instance called db2inst1 is created during DB2 installation, along with three users: db2inst1, db2fenc1, and dasusr1.

To create DB2 database instances on Linux, follow these steps:

Create groups for DB2:

groupadd -g 999 db2iadm1 
groupadd -g 998 db2fadm1 
groupadd -g 997 dasadm1

Create users for DB2:
```
useradd -u 1100 -g db2iadm1 -m -d /home/db2instN db2instN -p db2instX
```
where db2instN is the name of a user and db2instX is the password for that user. Create enough users to match the number of database instances.

Create the db2fenc1 user for DB2 in the db2fadm1 group:

useradd -u 1101 -g db2fadm1 -m -d /home/db2fenc1 db2fenc1 -p db2instX

Create the db2fenc1 user for DB2 in the db2fadm1 group:

useradd -u 1101 -g db2fadm1 -m -d /home/db2fenc1 db2fenc1 -p db2instX

Create the dasusr1 user for DB2 in the dasadm1 group:

useradd -u 1102 -g dasadm1 -m -d /home/dasadm1 dasusr1 -p db2instX

To create new DB2 instances, log in with root user and go to /opt/ibm/db2/V10.5/instance.
```
./db2icrt -u db2fenc1 db2instN
```
Create enough instances to match the number of databases.
To set the port number of the instance, edit the /etc/services file and add the following line:
```
db2c\_<instance\_name\> <instance\_port\>/tcp
```
where instance\_name is the name of the instance and instance\_port is the port number of that instance. Repeat this step for each instance.

Log in as the database instance and set the communication protocols for the instance:

su - db2instN
db2 update database manager configuration using svcename 
 db2c_instance\_name
db2set DB2COMM=tcpip
db2stop
db2start

Repeat this step for each instance.

Edit your firewall configuration to allow the new instances to communicate through their listening ports.